Chinese phones have a major issue with user friendly /logically user interface, few are nice to use, unlike Korean/Japanese /us phones, best to try before buy, ask xiaomi owners etc
One plus one used to use western developed cyangenmod ui , high quality, great reviews, but lost support with them, oxygen os which was developed by themselves is an example of better China developed os, but not as impressive or acclaimed as cyangenmod
To some users xiaomi is very frustrating to use, but to others they live with it
Same issue to high end /audiophile quality digital audio players from China, great hardware, but not nice /clunky /frustrating user interface. Especially compare refined /superb Koreans /Japanese /us ones