Broken online aspects mostly. The single player campaign was fun. Howrever, I wasted so much time trying to get to play with friends online, and with constant complaints about the broken voice-chat on the forums going unaddressed while they continued to roll out DLC, that leaves an unfortunate bitter after-taste. "We'll make money of those who are not having problems and ignore those who are," is not a very considerate attitude. Not to mention the story what utter pants and made no sense whatsoever!
I'd like a Borderlands 2 or similar, definitely. The RPG elements in a shooter made it far more involving for me than other shooters. Plus the whole pacing and tempo, allowing long-distance sniper shots or up-close Rambo style however the player felt. I'm just gonna wait until after release and check the forums, and this time when I ask and people say, "you'll have no problems, there are these workarounds," I'll ignore them and go by the number of people who are having problems! (although of course if Sony got their act together, a lot of this would be moot.)