Disappointing at all
I have my Mi Band 2 for a week now, and so far, I can give you the following impressions, maybe someone can give me a hint concerning my first point.
1.) I have a Samsung Galaxy S4 i9515GT, not the latest device, but quite common, and my main problem is that the band keeps losing connection about once a day, sometimes more often. Whenever that happens, the original Mi App displays "Connecting band", but nothing happens, and you can try to un-pir and re-pair, or switch bluetooth on and off, and all the other good advices you can read anywhere on the web, but that all doesn't help. The only thing that works then is rebooting the phone, which is a pain in the a**. Any advice why this happens?
2.) I was able to sync the band to Google Fit (S-Health which is my favorite app does not work unfortunately). Nevertheless, Google Fit keeps using its own step counter, i.e. it displays about 20% lower steopcount than the Mi App. The step count however seems nearly identical to that measured by S-Health, which gives more plausible values in my opinion, so overall the step counter seems to be quite accurate.
3.) Measuring heart rate works only on dry skin and the band connected closely to the skin, as soon as you keep sweating at your armwrist, the measured values are far too low or no measurement is possible. So if you sweat during sport, the measurement ist crap and useless. Besides, the standard Mi App does not offer continuous heart rate measurment, you have to buy another app like Mi Band tools für 2 EUR or so, there you can define intervals from one minute (so still less than continuos measurement by a dedicated chest-wrist based device) up to any minute-interval you want. Why does Mi not offer that at least as a default?
4.) App notification of the original Mi App is a bad joke, because no matter which app sends you a notification, it always displays the same icon, so unless you look on your mobile device, you cannot know which of your configured apps has actually had a notification. However, Mi Band Tools which you must buy offers this functionality, but you can only connect each app you want to be notfied to a hard-coded symbol in the Mi Bands firmware, no custom icons possible.
5.) Sleep tracking is not more than wild guessing. I was awake half an hour last night, walking around, which the band interpretes as "light sleep". And the wake-up time is wild guessing too, so nothing more than a gimmick to play with, but not related in any way to my sleep at all... If you keep lying in your bed awake for an hour after sleep, that is measured as "light sleep" as well...
6.) Smart unlock is playing lottery too. I find that extremely userful if you do not have to draw your unlock pattern each and every time you activate your phone. This feature works about 80% of the time, the rest 20% you are asked for the unlock pattern on my Samsung S4 anyway, even if the Band is connected and near the phone. So this is simply implemented in a very buggy way.
7.) Battery Lifetime is about 10 days with heart rate measurement every 10 minutes in the Mi Band tools app which is okay for me
8.) The phones battery life is much shorter of course.
Any comments appreciated. After all: you get what you pay for, I was very enthusiastic about the band 2 in the beginning, but after a week, most that's left is disappointment especially how bad the nice features of this gadget are actually implemented!