I have been using Xiaomi Mi4 for about 2 years and it is stilll performing great with no lags.
I find mi user interface to be the best and fastest among all. Has many useful features and avoiding other useless features in other user interfaces.
Has very good primary camera. Click some good pictures in daylight.
Night pictures and low light pictures can be better.
Front camera is also good. Click natural pictures.
Loundspeakers have pretty low volume. But sound om headphones is pretty good. Can be among one of the best. Has different headphone setting according to ever other headphones. Yhat is pretty unique.
Has very good built quality. Looks beautiful in hand.
It is totally a value for money phone.