No doubt this phone is one of the best phone of xiaomi. this phone build quality is very good. Display of the mi4i is very good. its viewing angle is good. Front camera of this phone is much better that other xiaomi phone in this budget. Past to year I am using mi4i but till date I am not facing any lag in my phone. Processor, battery backup, camera think ness of mobile is good. VOLTE is not available in this but speed of LTE is much better than other LTE phone. MIUI user interface is very good.