Xiaomi Watch S5 Review: Strong Hardware, Limited Software

Xiaomi continues to flood the smartwatch market. A few months after the Watch 5, which ran Google's Wear OS, comes the S5 variant. More accessible, it runs HyperOS, the manufacturer's in-house software, and carries a lighter specification. Gone are the electrocardiogram and electromyography sensors and the internal storage. What it keeps is the Oled screen, the large battery and dual-band satellite positioning.

That combination gives it arguments for anyone after an accurate, long-lasting model without moving to a sports watch with an aggressively technical design.

This review covers the device's design, software and measured tracking performance. It makes no claim about health, fitness outcomes or weight, and the sensor features listed below are described as hardware and screen functions only.

As ever, and regardless of where a product sits in the range, Xiaomi takes care of appearances. The Watch S5 has a substantial case measuring 46 x 46 x 10.99 mm and weighing 45.6 g, made entirely from stainless steel. Compared with the Watch S4, this model slims down by roughly a millimetre and gains thinner screen bezels.

On the right-hand edge sit two controls: a rotating crown that can also be pressed, with haptic feedback, and a flat button. The whole assembly is elegant, particularly since it surrounds a very well-judged 1.48-inch Oled screen. Without being revolutionary, that panel is highly functional: it stays legible in bright sunlight thanks to a maximum brightness of 2500 cd/m², close to that of the most premium models, and it does not dazzle once the surroundings are dark.

The Xiaomi Watch S5 comes with a fluoroelastomer strap that is pleasant to wear even when wet. It uses a conventional attachment and can be swapped without difficulty. Xiaomi also offers versions with a leather or braided nylon strap.

The Watch S5 carries a 5 ATM water-resistance rating, which covers showering and swimming.

The Watch S5 runs HyperOS, Xiaomi's own operating system. Although the manufacturer does not publish the amount of storage available on the wrist, it is possible to download maps directly to the case.

Anyone who has owned a smartwatch before will have no trouble finding their way around. The interface is driven by the physical buttons, the touchscreen and wrist gestures.

Starting with the buttons: a single press of the rotating crown wakes the screen, opens the main menu or returns to the home screen. From the home screen, turning the crown clockwise brings up widgets, while turning it anticlockwise reveals notifications. More generally, the crown scrolls through all of the menus.

The flat button opens a shortcuts panel for activating Do Not Disturb, battery saver and night modes, or Wi-Fi. Confirming a choice requires the touchscreen which, beyond that action, offers little more than the crown already does. That is no bad thing, since it lets each user pick whichever navigation method suits them. The touch panel's one exclusive trick is that a right-to-left swipe from the home screen changes the watch face.

Then there are the gestures for controlling the watch without touching it. There are three: snapping the fingers, shaking the wrist, or rotating it. Each gesture can be customised to trigger a quick action — rejecting a call, dismissing a notification, taking a photo — to start a chosen workout, to open an app, or even to exercise basic control over another device in the Xiaomi ecosystem.

Entertaining though these features are, they struggle to convince over time, simply because they do not work every time. It is not unusual to snap your fingers two or three times in a row before a call is rejected, which rather draws attention.

That is not a serious problem, since the gestures are entirely optional and navigation on the Watch S5 is otherwise trouble-free. What remains is the limitation that has dogged HyperOS year after year: navigating is all very well, but to what end?

The watch does without Deezer and Spotify. Xiaomi's operating system remains closed to third-party applications, which means making do with those preinstalled. Preinstalled apps can now at least be removed directly from the wrist, but the manoeuvre loses much of its point when nothing new can be added.

More happily, the watch relays notifications, which the large screen renders very legibly, and it can control music playing on the phone. The overall experience is still frustrating, all the more so given that other models benefit from Wear OS, which is far more capable in this respect.

There is also a microphone and speaker for taking calls from the wrist or recording voice notes. Both are of average quality, offering just enough to stay intelligible.

The Watch S5 syncs with the Mi Fitness app on iOS and Android. Clear and responsive, it is divided into four tabs. The first gathers the readings compiled by the watch, which the screen displays as step count, calories, heart rate and sleep information. The second allows a workout to be started from the app, the third configures the watch, and the fourth is given over to the user profile. Those last two sections are rather thin and offer few customisation options.

The Xiaomi Watch S5 covers the essentials with an optical heart-rate sensor, dual-band satellite positioning, a pulse oximeter, an altimeter, a gyroscope, a compass, a barometer and an accelerometer. Missing are the temperature and electrocardiogram sensors found on some rival models.

Dual-band satellite positioning delivers accurate results, in the city as well as in open countryside. Its traces are consistent, and markedly better than those recorded by a phone — in this case an iPhone.

As for the heart-rate sensor, there is little of note to report either. During a steady-paced running session, the Watch S5 recorded a heart rate very close to that measured by a Polar H10 chest strap used as the reference. There is simply an offset at the beginning while the watch settles, but nothing prohibitive.

Interval work produced a more mixed result: only the second half of the short 15-second accelerations at the end of the session was picked up and reproduced faithfully. It is as though the sensor needs a period of adjustment to take in abrupt changes of pace. Once the tempo stabilises, however, the data is entirely accurate.

The Watch S5 also records sleep, blood oxygen saturation, stress and menstrual cycle data, each presented as an on-screen reading.

815 mAh is the XXL capacity of this Watch S5's battery, and it does not disappoint. Under intensive use — receiving notifications, continuous heart-rate monitoring, sleep tracking and a daily activity session — the watch lasted 14 and a half days. That is a fine result. Note that the always-on display was not enabled during that period.

Recharging the Watch S5 takes around 1 hour 25 minutes. That is a little slow, but hardly an inconvenience given how long the watch lasts between charges.

At this level of the market it is difficult to find a rival as competitive. A little better finished and longer-lasting, the Watch S5 is a more rounded product than the Watch S4, though it still sits slightly behind the Garmin Vivoactive 5.