Xiaomi Watch S1 smartwatch review: Allrounder with shortcomings

Xiaomi makes use of a stainless steel case for the S1. This not only intended to make it particularly robust, but also to give it a high-quality appearance. This is accentuated by a fine texture which, according to Xiaomi, is the result of hand-polishing by traditional watchmakers. The use of steel is clear here: We weighed 65 grams with a leather strap, making the Xiaomi noticeably heavier than, for example, a Huawei Watch GT Runner with its plastic case. Sapphire glass is used for the 1.43-inch display. The materials are haptically very pleasing and well-made. No scratches were detected during examination and testing, but the glass is susceptible to fingerprints. There are two buttons on the right side of the watch that stick out: their pressure point is good, but they prove to be slightly loose when you fiddle with them. The buttons can also be rotated, but this has no function in use.

Underneath the keys is a speaker and on the opposite side of the case are the microphone openings. The watch thus offers the necessary hardware for phonecalls, a voice assistant and music playback - more on that later. Wireless charging (Qi standard) is supported and functions without any contact to the case. The straps correspond to the 22 millimeter standard and can be replaced cheaply. The original parts have small levers on the spring bars, so that replacement without tools is possible

The optical sensors for the extensive monitoring features are located on the plastic underside. In addition to pulse rate, blood oxygen is also monitored. Moreover, the Watch S1 offers Bluetooth, GNSS, a barometer and NFC for contactless payments. However, only the Xiaomi Pay service is installed, which currently does not function with any German banks (Note for international readers: compatability with Xiaomi Pay may differ from region to region). Payments were therefore not possible with the watch during the review. The watch is also capable of establishing Wi-Fi connections on its own.

The watch has a microphone and a speaker and thus enables telephony as long as a smartphone is paired via Bluetooth. A standalone data connection is not possible due to the lack of a SIM card. The connection is good enough for both parties (caller and responder), but the speaker on the watch is not very loud. Calls can also be carried out via the watch. However, there is no access to the entire phonebook, but only to the call list. If the desired contact cannot be found there, then the smartphone has to be pulled out. Calls via the voice assistant are not supported.

Notifications from messenger apps, mail programs and other app notifications are displayed as pop-up messages in all menus and, if desired, also during sports sessions. The messages can still be displayed in the message menu after they have popped up. But if a message is opened and closed, it disappears from this menu. The smartphone has to be taken out for a second look later. Emojis are displayed by the watch, but not images. Voice messages cannot be played either. Replies are not possible at all with the watch, even preconfigured quick replies are missing. Reading messages on the watch has no influence on the "read" status on the smartphone.

The Watch S1 provides comprehensive information about daily activity goals, which are displayed in colorful semicircles. Calories burned, steps taken and minutes spent in motion are indicated. The respective target values can be adjusted individually. Furthermore, the smartwatch also shows blood oxygen saturation and stress levels. The stress level is given on a scale from 1 to 100 and is based on heart rate variability. Blood pressure measurements are not offered, while VO2max values are provided during training.

The Xiaomi Watch S1 performs as it should in terms of heart rate measurement. A Polar H 10 chest strap was used as the comparison device under testing. Both devices measured the resting heart rate identically. This was also very much the same for training: Both the average heart rate and the peak values only deviated by 0.6 percent.

The Watch S1's sleep tracking also proved very reliable under testing; waking phases were always detected. If the corresponding menu item is activated, the smartwatch not only differentiates between light and deep sleep, but also tracks phases of REM sleep. The quality of the sleep is evaluated by the app, and there is also additional information about the importance of the sleep phases and tips for better sleep. The results can be displayed in the form of days, weeks or even months. Values for pulse and blood oxygen saturation during the night are also displayed.

The watch itself also displays the sleep data, but the menu item has to be clicked on specifically for this. A downside is the lack of an automatic notification upon waking up. The possibility of using the sleep data for the alarm clock is also missing; the Watch S1 does not offer a smart alarm function. Under testing, there was one night when the watch was accidentally turned off due to movement.

Xiaomi does not provide any information about the installed SoC or memory. We could not determine any system stutters in practice. Animated clock faces also pose no problem for the watch. Switching between the individual pages with widgets is just as smooth as scrolling through the menus and apps. Even several quick inputs in succession do not cause the system to stutter or even crash.

The memory provided is needed for additional watchfaces, training data and apps. However, app selection is extremely limited; only four are currently available in the store. Saving music directly on the watch is also not possible.

At the time of publishing, the Xiaomi Watch S1 was available at Amazon US for US$ 270.  Those who can do without Qi charging can get the otherwise equally configured Xiaomi Watch S1 Active for US$ 221.