I am using MI 4i for the past one and a half year and Mi 4i is the first smartphone that Xiaomi has launched ahead of all other markets. it is the coolest gadget I got .i used it very well.and I did’nt face any problem till now.the main bad features of this phone it is not supported by both 4G SIM. only one slot is supported by 4G SIM.nowadays I got some battery heating problem and this is due to over using of phone .other than this I did’nt find anything else.it is one of the cheapest phone with such a features.as compare to others.