Flagship specs and long-lasting battery life come in a small package, but some questions loom

For a tech company with as diversified a portfolio as Asus, I have to wonder why it isn’t doing more to grow in the mobile space, especially with the Zenfone 9. From its first phone to its latest, the company hasn’t been afraid to play around with what a phone can do and, in the process, make mistakes. Those experiments have included using an Intel Atom chip, obsessing over zoom lenses, and going all out on flip cameras. Its latest strategy is to pack as much power as possible into as small a space as possible. The engineers did a pretty good job with the Asus Zenfone 8, and the feedback the company got has encouraged it to trim down further and power up the Asus Zenfone 9. I’d say it’s a pretty darn good showing.

As with the Zenfone 8, Asus is pulsing out the availability of the Asus Zenfone 9. It’s starting with its home market of Taiwan as well as Hong Kong, most of Europe, and the United States. No dates have been announced just yet.

The phone will be made available with three sets of memory combinations: 8GB of RAM with 128GB of storage for $700, 8GB of RAM with 256GB of storage for $750, and 16GB of RAM with 256GB of storage for $800. Now that's bang for buck if I have ever seen it.

Asus tells us that the device should work outright on T-Mobile. It has also said it will be certified on AT&T, but it hasn't made it clear when that will be official. Asus also confirmed to Android Police that it didn't target the device for Verizon. The US SKU should be compatible with almost all LTE and Sub-6GHz 5G bands on AT&T (minus LTE Bands 14 and 29), T-Mobile, and Verizon (minus LTE Band 13).

During our review period, we couldn’t activate the device onto Google Fi (T-Mobile and US Cellular), so we tested it on T-Mobile via a Tello SIM. The company says there should be no issue with Google Fi support and that it would need to debug this specific instance before commenting further. As of the very morning this review goes out, we just received a software update and were able to get Google Fi to provision our Asus Zenfone 9 unit. We expect to continue assessing the device and will have updates to this review in the weeks and months to come.

Asus is prideful about going small with the Zenfone 9. It was the only OEM to produce a premium-tier smartphone with a physical footprint of less than 150 × 70 mm last year, and it’s managed to keep under the same threshold this year with a 2% reduction in area compared with the Zenfone 8. Thickness increased by 0.2 mm on the Zenfone 9, but it still resulted in a volume reduction of 0.6%. When the design is about having it all while being so small, you’d expect every aspect of the phone to be built around that same theme.

Aesthetically, I’m not impressed. The back features a newly developed texture that feels like a foamy knockoff of the sandstone finish that OnePlus had mastered long ago. That said, this polymer-coated plastic material does achieve the objectives the company set out: the rough-ish surface hides fingerprints well and clings to your touch more than the matte glass treatment on the Zenfone 8. That’s especially true with the elimination of the sweeping tapers to the side edges in favor of narrow-radius bevels going down to the aluminum chassis.

There’s an IP68 certification for water and dust resistance. Even with that rating, I have my doubts the rear will age gracefully, especially as I've watched the silkscreened branding elements fade away over the course of a week. You might make good use of the brittle plastic bumper case that's included in the box.

There’s more to the Asus Zenfone 9 than just appearances or a lack thereof. The company is sticking to two rear cameras this year, but they don’t share a single piece of cover glass this time around. The 50MP main sensor — which we’ve seen on the Nothing Phone 1 and OnePlus Nord 2 — is slotted under its own lens elements into a six-axis stabilizer system. Movement on five axes is physically corrected by a gimbal (X, Y, Z, yaw, and pitch). The one exception is roll and that’s covered by electronic stabilization. There’s also a 12MP ultra-wide sensor that gets an equally obnoxious housing. Those two gigantic circles certainly do add to the overall aura, though.

Another big difference between the Asus Zenfone 9 and its predecessor lies on the right side of the phone instead of underneath the display. That’s right: the optical fingerprint sensor is gone. The manufacturer has swapped to a capacitive fingerprint sensor, which is now on top of the power button. The company says that the component change is more conducive to one-handed use as it enables time-tested shortcuts through gestures like multitaps, long presses, and swipes. We’ll get into exactly what they can do in the software section below, but for now, all you need to know is that the sensor scans super quick.

The selfie camera resides in a punch-hole in the top-left corner of the display. It’s the same 12MP unit from last year. If you find this style of selfie camera to be obtrusive, well, you’re going to find this camera obtrusive. And if you don’t, you won’t.

The display is more or less the same 5.9-inch Samsung OLED panel we saw with the Zenfone 8. Asus says its color has been calibrated at not just one, but two brightness levels this time for increased color accuracy. My strengths aren’t in display calibration, but I was able to discern the very slightest uptick in warmth and magenta tinting and determine a slight net gain in the new screen’s accuracy. What was otherwise a good panel in the Asus Zenfone 8 definitely holds up well in the Asus Zenfone 9 with wide viewing angles, brightness that cuts through sunlight, sharpness at 446 pixels per inch, minimal color shifting, and great HDR10+ output.

These days, you might think of this 5.9-inch display at 20:9 aspect ratio to be downright diminutive. I don’t think you’d regret watching a movie on the Asus Zenfone 9, though. You've got a lot more room than you think you do when you're on a cramped intercity bus. I've been on my fair share of those rides and have had phones with lesser displays on them.

It’s somewhat surprising to find audio such a priority for Asus considering that space is at a premium here. Of course, there are all the important Bluetooth codecs like LDAC and aptX Adaptive. Audiophiles will be glad to know, however, that the company has kept the 3.5mm audio jack.

The stereo speakers, oriented as a top tweeter and bottom woofer, have decently sized resonance chambers to amplify and spread their waves around. I definitely annoyed some diners sitting at neighboring tables at the cafe when showing a YouTube clip to my brother. The in-line amp and the drivers are Qualcomm parts. Whatever you think of them, Asus has its bag full of tricks like bass oversampling and soundstage widening, plus a little tuning help from its friends at Dirac to squeeze extra oomph no matter which way you listen. I can certainly say I had some fun times listening with my poppy Grados plugged in or my Jabra wireless over-ears.

Software skins have never just been about the launcher experience, and ZenUI takes everything else pretty far. The launcher is close to the design of a basic Android Open Source Project build with a 5 × 6 grid and an app drawer with app search. The Google Feed pane resides to the left of the home screen. Asus has stock apps for the clock, contacts, dialer, file manager (I find this one particularly nice compared to most of what’s available out there), gallery, and weather. Most of these are fine for what they are, but are definitely give or take for someone who’s been using the stock Google apps for a long time.

There are a few specialized apps, including the AudioWizard tuner (powered by Dirac), which features a 10-band graphic EQ, and Game Genie, which just opens up a dedicated panel of performance settings and includes the ability to set up touch macros.

Just a quick personal word with Asus, here: can you ease off on these wide-radius corners in split-screen mode? They’re ridiculous for video and could block some user interfaces. Thanks.

Asus has been serious about equipping ZenUI for one-handed use with lots of shortcuts through gestures, gestures, and even more gestures. Most of these gestures in the ZenTouch suite are tried and true, like the double tap to wake and lock feature that LG once made famous. However, some of them, like drawing letters while the screen is off, still don’t make sense to me and probably never will. The fact that they’re still around probably means someone out there must be a fan, though. There’s an “edge tool” that brings up a panel of apps and tools you can access picture-in-picture while in any other app, and there’s also a double-tap-on-the-back shortcut that spices things up. I’ve been using it to take screenshots, and it’s been a joy to use for the most part — I did have a couple of false positives from moving the phone between portrait and landscape orientation, but I insist it’s more good than evil.

The fingerprint-power button combo gets the most mileage. Double pressing and long pressing can open up different shortcuts — Google Assistant, simple dictate-and-paste, opening up an app, toggling specific settings like Do Not Disturb or the flashlight, speed dial — while swiping may allow you to check notifications, refresh or scroll on a webpage, or control your media. I like having all of these options because any combination of them makes it easier and quicker for me to get to what I need from my phone. In other words, complications that make things simple.

A fun quirk I’ve noticed on these Zenfones is that Asus gives users straight-up access to the developer options. No need to tap the build number seven times. That one’s for the nerds, I guess.

Asus is still only committing to two annual OS upgrades, and two years of security updates coming every other month or sooner. That’s disappointing when competitors like Samsung are offering up to four years. This means the Asus Zenfone 9 is likely to get updates through to Android 14, but if you buy a Samsung Galaxy S22 today you’re likely to get at least Android 15 and perhaps even beyond.

My Asus Zenfone 9 came with 16GB of RAM and 256GB of storage, so you can probably already guess that it can dominate tasks and keep plenty of apps in memory. Credit to the engineers for cramming in more cooling — the company says there’s about 230% more thermal material inside the Zenfone 9 that covers 13.5% more surface area than in the Zenfone 8. I’m not saying that the phone didn’t get warm, but considering that I shot a whole bunch of 4K video in sunny 95°F weather, I can definitely say that the phone didn’t slow down nor did the battery drain as quickly the way I expect most phones to do in those conditions.

The Snapdragon 8 Plus Gen 1 is extremely performant, though I’m not sure you’d believe me if I told you the most I’ve done with the Asus Zenfone 9 is play some not-so-intense 2D strategy games (Dicey Dungeons and Krumit’s Tale, if you need to know). The chipset did lend a hand in driving that video shooting experience I mentioned above — this is about as much praise I can heap on Qualcomm without doing something disingenuous as humiliating myself in PUBG for 5 minutes or performing benchmark tests that will probably be thrown out of the database in a few months.

Battery life has been gangbusters for me. Standby retention has been amazing and my YouTube consumption taxes this phone less than it does with most others.With the regular dynamic mode, the phone can easily last two full days on a single charge, though I have yet to hit anywhere near 15% since I’ve been charging nightly out of habit.

With further testing, I could see myself limiting the maximum charge level to lessen battery wear while still getting a full day’s use. There’s also a high performance mode that turns on dual-band Wi-Fi use and constant 120Hz refresh rate among other tweaks. I'd estimate I could last a day with a full-capacity battery, though at the cost of the phone's useful life.

Wireless charging is once again nowhere to be seen on a Zenfone. That’s especially unfortunate considering that the 30W charging block is a honker to carry around, and it’ll almost certainly take up both spaces of a North American power outlet. Asus says it didn’t want to compromise on its priorities for device performance and size — we could’ve potentially seen a smaller battery. Paired with the short two-foot USB-C to USB-C cable included in the box, the wall wart does top off the phone quickly. Plugging in at 41%, it took 6 minutes for the Asus Zenfone 9 to reach 51% and an additional 30 minutes to bring it to 91%.

The cameras on the Asus Zenfone 9 are good. They’re not great like the Pixel 6 or Galaxy S22, but they’re a step above the Nothing Phone 1. But you probably didn’t need a written hook here to judge the samples below yourself (though I will be providing guidance along the way).

Processing definitely needs the most improvement. Sharpening is my main bugbear. It’s just a bit too pervasive, and where it doesn’t introduce pure problems like color banding — which can instantly ruin golden hour HDR scenes — you can just feel it giving some off vibes to details.

You’ll notice in this whoopsie of a capture where everything’s out of focus that the edges have a certain, odd definition to them.

Exposure adjustments can also be a challenge for the Zenfone 9 as well. It’s not so much in stills as the dynamic range is wide enough where you can pull decent stuff from either extreme. I’ve had a couple of worse blooms than the one you’ll see in this 4K video sample from the ultrawide camera, but this clip definitely captures it in action.

Here’s another 4K sample from the main camera. You’ll see the six-axis stabilization system in action here and it does its job. A bit of a shame about the low-light performance, though: even a slow pan can cause dizzying blur.

I prefer the full-resolution stills I’ve been taking with the 50MP sensor as they seem to feature less sharpening than the 12.6MP pictures (quad-bayer binned) it puts out by default. One thing I can respect is that color across all media stays quite accurate to life.

I could go into the debate about telephoto versus ultra-wide cameras, but I'm generally satisfied with the field of view of the ultra-wide sensor on the Asus Zenfone 9 as well as the overall software treatment — that is, with the same pros in color and cons in details.

For a $700+ device, I don’t think “good” is enough. The hardware provides a strong foundation to work off of, but it’ll take a lot of code work from Asus to get all the little bits right. On the flip side, I did find the camera to be snappy and responsive, the gimbal straightening guides useful, and the light trail capture mode easy and fun to use. At the end of the day, I’d still use this camera and be okay with it.

Yes, but it’s not for everyone. I’m in the camp that’s searching for top performance and endurance doing all the things one does on a phone. This is the best value out there. I know “compact flagship” have been the buzzwords around town, but in a sense, it seems like the small size is more a function of all the shortcuts Asus packed in here than the other way around. To be fair to Asus, the company believes its competitors have cornered the market on big phones and that its best chance for success is to go the other way.

You might consider some of the compromises the Zenfone 9 makes to be failings. You might just think bigger actually is better. Maybe a Samsung Galaxy S22 or a Pixel 6 could do you better with their lower prices and mainstream appeal. I think they’re both fine options that come with their own established ecosystems and value adds.

But if you want fast and furious without the fuss, then I don't think those phones should overshadow what the Asus Zenfone 9 offers — including how it makes use of its size.

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Jules joined the Android Police team in 2019. Before that, he was at Pocketnow. He loves public transportation, podcasts, and people in general. He also likes to take views from the bigger picture in technology from how people are attracted to it to how it's utilized across every other industry.