how does your smartphone work as an activity tracker?
<answer> If you are looking for a basic activity and sleep tracker, then the Xiaomi Mi Band does the job very well. <context> Verdict. If you are looking for a basic activity and sleep tracker, then the Xiaomi Mi Band does the job very well. We wouldn't recommend it for those who can get by with a smartphone's built-in sensors, as any of the numerous available fitness tracking apps provide the same functionality.our smartphone, being in your trouser pocket, does a much more accurate job of tracking certain types of activity than the Mi Band can, but you can't make them both work in tandem. The flip side is that it is extremely useful in places and at times when you cannot carry your smartphone around.