I have been using note 4 from past 1 year and I should say that till date I have not experienced any difficulty or any kind of fault in it. I am impressed by some of xiaomi features like three finger screenshot, two finger slide of notification etc.
Camera quality is also good though. And the new update also has many filters in it. Many people say xiaomi phones gets heated but till date I haven't experienced any such thing. So overall I like my phone.