I first bought Mi band 3 around 3 months back..But on the same week Mi band 4 was launched in China .. so I returned band 3 and started waiting for band 4.. got it as soon as it went on sale (19th September).. so now ia have been using it for about 2 weeks.. Main features :- The coloured display makes it look refined and elegant. The options for sleep tracking and heart beat monitoring are quite accurate and gives you lot of real-time data. Options to add band faces in band display settings make it very much costumisable and personal. To me one of the best thing is the option to change music tracks, adjust volume by tapping on the screen. This is particularly helpful when one works out with music being played in the background using Bluetooth speakers.. the option to change track makes it a matter of a few taps on your wrist.. and voila new pumping music is on.. All in all I am a highly satisfied costumer.