As usual xiaomi gave us biggest surprise by launching miui 9. MIUI is the best rom in case customisation and stability.It offers great user experience and give more control over your device.Battery backup was excellent compared other roms.There are many hidden features which are not known by the users
Like three finger screenshot , scrolling screenshot, quick access ball, etc.

     Coming back to the MIUI 9   we cannot see a radical change,but there is some stability  improvement are there

Main features of miui 9

 1.Split screen

   This feature was introduced in noughat roms     although it was not available for xiaomi users.
   Split  feature all along with existing features give  a uphand for miui users.



2.Homescreen customisation                            
Another exciting feauture is home screen editing.It has been redesigned and apps can arranged more quicker according to your needs

3.Notification filter                                          

It helps you avoid unwanted  notification annoying you!

4.Quick app launches                           

By introducing this feature xiaomi claims it will load apps much faster than any roms available.They have added tweaks to improve fast launching of apps




These are the key features from miui  which we thought great indeed, for check the following link

Pic courtesy: http://en.miui.com/forum.php?mod=viewthread&tid=722755&highlight=Miui%2B9%2Bfeatures