1. ENEMIES keep MOVING about the screen DURING PLAYER TURN in combat.
The enemies often keep/start randomly moving during player's turn. It gets pretty comical really...you try to hit multiple turtles, for instance, with an aoe spell and they just keep "drifting apart". Once an enemy drifted across the entire screen right to my ranger before I had time to complete the ranged attack.

2. ENEMIES MOVE THROUGH OBSTACLES/FLOAT OVER WALLS ETC.
AI often travels directly to target, ignoring the geographical features of the map altogether, be there walls, stones or anything else. I've had enemies float up the walls instead of using stairs etc.

3. NAME TYPING in CUSTOM CHARACTER CREATION often results in letters typed out of order.

4. ARMOR CLIPPING ISSUES
Still abundant after the last patch. Seeing underwear through armor often (seems to get more apparent when zoomed all the way in).

5. POOR ICON/BUTTON RESPONSE (problem that carried over from D:OS).
Players often need to click attack icons twice or more before the button activates. Failed attack icon activation frequently results in characters traveling to cursor instead of performing attack, which is quite frustrating in battle.

Same can be said about hovering the cursor over icons. You often have to do it more than once before info decides to pop up.