Let's see.
1. Toning down the environmental effects. Its way too much. I mean less barrels, Cantrips not starting fires everywhere. Npc's not acting like a MLB pitcher every fight.
2. Action bar changes/ui improvements
3. Jump and Shove and disengage. Making them more like 5e
4. Party movement. Im not a fan of the chain mechanic.
5. Mages and spells need work. No cleric spells for mages. A spell book or something. anything other than spells just thrown on an action bar with everything else.
7. Every click, action, or interaction turns into a laser light show. It just makes it feel so arcadey. Spells are beautiful and Im amazed with what Larian has done with them, but really the more mundane things or melee actions don't have to be so over-the-top.
There is a lot to like in the game. Some of these things not so much.