Depends, really. I never get to into games enough to start running spreadsheets about what weapon does the most damage per shot/hit or if I jump off of this pixel *just right* I can land on this hard to see ledge and Bastard-Snipe until I run out of ammo.
So I guess I'm somewhere between Average and Really Good depending on the game I'm playing. I rarely am at the very top in FPS rankings, and just as rarely at the bottom. I have, however, been described as "crazy good" at Donkey Kong Country before. That was pretty sweet.