It measures heart rate and steps very accurately. Especially in steps, I didn't expect such precision in exercise. The screen is very good with over 350 online faces for all tastes. The battery is satisfactory.

The top button, although it rotates, does nothing.
The 24-hour oxygen recording doesn't work even though it is advertised in the watch specifications. It works for heart rate and blood pressure, but of course, the blood pressure values are just random.
The stopwatch and countdown do not work in the background, so the screen remains on.
The application is very simple and has nothing beyond the very basics. It doesn't even track heart rate during sleep.

If the oxygen worked as advertised, then the watch would have no rival in this category and even higher.