1) You should not buy red mi note 4 because its a hybrid slot either use two sim or one SD card.
2) No fast charging support it takes around 3hr to charge 4100 mh battery. when we r travelling and in a hurry we face d problem.
3) Front camera is not good and the camera does not support 4k recording and inbuilt microphone not that great.
So if your content create like recording video with your phone after sometime cannot upgrade your video quality because it only record video upto full hd . So it might draw limit line.if u want to upgrade ur video quality in future.
4) No gorilla glass protection.