I don't even know, as the games I tend to enjoy most rarely require incredible amounts of skill - or at least, if they do, I don't notice. Either that makes me someone who generally sucks, or it makes me someone who finds things effortless.

I feel like I'm average at all kinds of games, really. I don't like PvP much so it's seriously hard to tell what I'm great at. Any game I've played PvP with generally can end up varying almost every time, sometimes I'm really good after a while and then the next game I'll be terrible, sometimes I'll go up and down like crazy from MVP to MUP (Muppet/Most Useless Player) almost every other game.

Single player games, though - too hard to know what I'm good at and what I'm not. Can you really be bad at JRPGs, adventure games, etc? I don't know. RTS I enjoy and seem to be able to finish campaigns on. Same for TBS and 4X. I feel this makes me competent, I'm not sure about 'great'.

I can't play Fighter/Racer games for long enough to get good, though. Not since the original Hot Pursuit, anyway.