I bought this phone last year.since then I have no problem.be it Camera, Screen size, processor, RAM, touch screen response.this phone uses MIUI which is developed by Xiaomi.MIUI MI user interface.
Internal memory is 16Gb which is very good.
Battery is awsome much better than others.
I had a little confidence when I bought xiaomi mi4i.but when I started using the phone , I did not believe The features.Xiaomi is great.i am not saying that you should buy this phone but you can taste the features on a phone i.e much cheaper than this phone like Xiaomi Red mi 2 and Xiaomi Red Mi.and also xiaomi Red mi Prime.