1. Bad translation/ text. Especially when you miss about half the story because of it.
2. Bad voice acting. If you can't make it good, don't use it.
3. Glitches or bugs that are obvious and easy to remove, still in the game.
4. Too easy battles/ skill system or no challenge at all. I'm no fucking Mainstream One button smasher, I grew up with games as hard as Donkey Kong Country and as complex as Final Fantasy 8
5. Bad mapping. Houses/ areas in wrong dimension, cloned NPCs and repeating design. Ruins it for me. No matter how good story/ gameplay may be- if my first look is on a map where there's no thought behing- forget it.