Those articles are way too generalized. BGR calls MIUI 7 "firmware", and they make a blanketed statement that Mi 2, Mi 2S, Mi 2A, Mi 3, Mi 4, Mi Note, Redmi, and Redmi Note all will be based on Android 5.1?? Yea right!!
Status bar icon changed a bit.When turned on there is white circle behind insted the icon itself becomes white.Also some widget on top of icons problems (sometimes) and gapps from google installer not fully working, play store cant connect, chrome not logged in etc. Some stock icons changed. Basically its same as miui 6 only faster. Settings menu changed a bit. Thats all from my 5 minutes with v7
I'll keep updates when notice,.
Also some free themes.
Gallery background is now white.
Gapps fully working, guess its just needed some time.
Thats it for now, basically its same as v6 the only major improvment is the speed the rest is just small UI update.