1) A setting for locking the camera over the right shoulder, or just a proper shoulder-swap command. It's a bit annoying to have to aim every couple minutes to smack the camera back to where it should be. I've never played a third person game where the camera just sort of meanders like this.
2) Camera and aim sensitivity dials. Keep them separate because the aiming feels good to me but I would love to be able to whip the camera around faster when I'm not aiming.
3) This game has an absolutely gorgeous map, but for the LOVE. OF. GOD. let us turn various icons on/off. The current situation has dampened by excitement for hunting down collectibles later.
4) A way to immediately compare stats on a weapon/outfit you're looking to buy related to what you currently have equipped. I know the game doesn't have a huge breadth of options when it comes to this but it would still be convenient.
Those are my main, fairly minor gripes. I'm sure all of these changes would be more complicated to implement than my non-game developer brain would appreciate, but they would really help to completely smooth out what is already a very smooth experience. In any case, the game is amazing.