1. No auto-attack. Having to hold 'R' to attack is a huge departure from the series, and needlessly makes it more complex to play, even during simple battles.
Solution: Add auto-attack back in the game.
2. The loot scanning and the lack of clear loot markers makes the game infuriating to play. Looting is something I find myself doing more than 50% of the time, and it is a pain. Having to rotate the camera over and over just to locate loot that I can't easily see on the screen is a complete waste of time. It gets even worse when there's trees and crap in the way of the camera. Like really, this needs to be fixed ASAP.
Solution: Automatically show all loot on the ground with text labels, noticeable glows/sparkles, etc. Get rid of the scanner altogether. It's not needed.
3. UI is terrible for equipping items and such.
Solution: Bring back paper dolls or just make a better UI. I don't even think the upgrade feature works.