Xiaomi's Mi 5s hides a fingerprint reader under its glass

There's also a larger Mi 5s Plus with a dual-lens camera.

We were already big fans of Xiaomi's Mi 5 flagship smartphone, so it's only natural for the Chinese company to build on this model's success by bringing us the Mi 5s. It should be no surprise that this dual-SIM device -- which has ditched the glass body in favor of metal -- packs Qualcomm's latest and greatest Snapdragon 821 chipset (as featured on the ASUS ZenFone 3 Deluxe), meaning it offers not only improved computational performance but also super speedy tri-band 4G carrier aggregation. As a bonus, it features up to 128GB of fast UFS 2.0 storage plus up to 4GB of LPDDR4 RAM, and NFC is still there on the back. But what really got our attention this time is the new under-glass ultrasonic fingerprint reader on the front.

At today's launch event, CEO Lei Jun spent a good amount of time explaining the merits and challenges of integrating ultrasonic fingerprint technology into his phones. Xiaomi had actually been exploring this option since October 2014 while planning for the Mi 5, in the hopes of avoiding the need to cut a hole on the glass for the fingerprint sensor. That way it'd be slightly cheaper to make, more aesthetically pleasing and more durable. Ultrasonic also tolerates dirty fingers better than its capacitive counterpart which would solve a big pain point. Just to be safe, Xiaomi actually prepared two prototypes for the Mi 5 back then: One with a hole on the glass for the conventional capacitive reader, and another without a hole courtesy of an earlier version of the ultrasonic sensor.

Of course, the Mi 5 eventually went with the capacitive button solution, as it wasn't until July this year when Xiaomi finally settled with Qualcomm's Sense ID ultrasonic fingerprint sensor. Hence its debut on the Mi 5s. Even though this ultrasonic solution works underneath glass, Xiaomi still carved out a little dent to help guide our fingers to the detection area -- which should come in handy if we want to unlock the phone just as we're pulling it out of our pockets.

Another highlight of the Mi 5s is its main camera. Much like the Nexus 5X, Nexus 6P and HTC 10, the Mi 5s takes the large-pixel approach by using Sony's 1/2.3-inch IMX378 CMOS, which offers a lower 12-megapixel still resolution but better sensitivity using large 1.55um pixel sites (these specs are in fact identical to those of the IMX 377 used by the three aforementioned smartphones). The camera also comes with an f/2.0 aperture, a dual-tone LED flash, phase detection auto-focus, auto HDR and video recording of up to 4K resolution at 30 fps. Xiaomi is quite proud of this new imager, so much that it has a gallery of sample photos for us to gaze upon. Flip to the other side of the phone and you get a 4-megapixel selfie camera with f/2.0 aperture, 80-degree wide-angle capture and real-time video beautification at up to 1080p.

Much like its predecessor, the Mi 5s is sticking with JDI's 5.15-inch 1080p display rather than pushing for the sharper 2K resolution, which is good news for the already larger 3,200 mAh battery. It's also just as bright as before at up to 600 nits and just as vibrant with the 95 percent NTSC gamut. What's new this time is that it's a force-sensitive touchscreen on the 128GB version, which is a first for Xiaomi, though the company didn't go into detail about how it'll be implemented in its MIUI OS' interface.

For those hoping to use the Mi 5s to control your TVs (and home appliances, for that matter), sorry, the old infrared blaster is gone, but there's no stopping you from casting content from your phone if yours is a connected TV.

For those who reside in China, you'll be able to pre-order on September 29th, with the base model (64GB storage with 3GB of RAM) asking for the usual 1,999 yuan (about $300) and the high-end version (128GB storage with 4GB of RAM) going for 2,299 yuan (about $345). It'll come in four colors: Dark grey or gold if you want the brushed metal finish (like on the cheaper Redmi Pro), and silver or pink with the matte finish. There's also a 79 yuan (about $12) pixel cover case, but it's sadly a shameless rip-off of HTC's Dot View case.

At the same launch event, Xiaomi also unveiled the Mi 5s Plus which features the same Snapdragon 821 chipset but clocked faster (2.35GHz instead of 2.15GHz), a larger 5.7-inch screen from Sharp (but lacking force sensitivity), a bigger 3,800 mAh battery, a different metallic body design (no plastic antenna lines and the conventional fingerprint reader is on the back) and a 13-megapixel dual-lens camera. Similar to Huawei's implementation on its Leica-enhanced P9 and P9 Plus, the Mi 5s Plus uses a combination of an RGB sensor and a BW sensor -- both Sony IMX258 -- to produce more detailed and cleaner images, though each of the them can also be used independently as well, especially if you want to dabble with artistic black and white photos.

The Mi 5s Plus will be available for pre-order on the same day as the Mi 5s, with the 4GB RAM + 64GB storage version going for 2,299 yuan (about $345) and the 6GB RAM + 128GB storage model going for 2,599 yuan (about $390).