First the problems 1 Phone has become little bit slow 2 Takes long for dial and hang up screen to appear also takes long to dial and hang up. 3 System Navigation is not implemented properly 4 sometimes swiping up to go back, opens recent apps list
Now the features that are removed 1. Block messages by phrase(Removed since Pie) 2. pro mode in Video 3. Downloadable scenes for Camera from Galaxy store 4. Many scene modes are removed like dual camera click and all. 5. For dual SIM, the Call, Data and Text selection panel is moved to the very top, 6. So you have to swipe down twice to switch Data, Text or Call from one SIM to another.
Unchanged 1. Battery performance is the same in fact little on down side. 2. Shitt grade icons, like that of Camera which gives your 80K phone a look of 15K mid ranger