I use mi band for 16 days. I really impressed by battery life 1 days - 55% left. Looks like declared 1 month from one charge is a real number. To be honest, I guess this is first time when declared number matches real experience.
On the other hand the activity detection accuracy is very questionable. I see "run" records for day I did not ran. But today morning I was running about 15 minutes, meanwhile mi band registered 1 (!) minute and 92 meters of distance. This is disappointing.
During this 2 weeks I use the band as my primary alarm - works well, sometimes I have a feeling that smart alarm really helps and I feel really fresh mornings, sometimes I'm not that sure. But anyway, I do not need to keep my phone near with my bad any more.
What else can I say?
I wear mi band together with my watch, on the same wrist. Again - no problems so far.
I also wear mi band 24/7. So far no problems with water. But I did not try to swim with the band, official FAQ say that one should not swim with a band.
I'm sure that this is not the last post about mi band, so follow the tag: "mi band"