GOTY 2011 - I'd have to say Minecraft, the wonderful blocky game that sucks your productivity very dry.
WGOTY 2011 - I haven't played very much this year, so I really don't know...
Suprise 2011 - I'd say Sonic Generations. When I learned everything about the game so slowly, from the levels that'd be there to even the music they'd put in, (boy was I happy when they made the Door Into Summer remix for the collection room :D) it was a long stream of suprises!
Letdown 2011 - Again, I haven't played much, and I don't have any really awful games from this year, or even letdowns, so this will remain unanswered.
Best this year - DOOM. Yeah, I said that. DOOM. I just played it, almost done. Did I mention I was dead frickin' serious that I just started playing DOOM this year? It's 2011, days until it officially is 18 years since the release of the game, I'm 13, and I have seriously never played DOOM until this very year. Call me a horrible pile of sadness as you will. :P
Worst played in 2011 - Daikatana. I only played 5-10 minutes of it and I officially know it sucks. My opinion on it is higher than most others since I actually suffered through a little bit of it, and even from those 10 minutes, I could write a list at least a page long of why it's bad.
Since I feel like it, I'll add my own tiny category;
Most anticipated games, even outside of 2011 - Super Meat Boy. I still haven't gotten my grubby hands on this meaty game yet. But I (unfortunately, due to a stupid feature related to Amazon wishlists, telling you "hey, someone related to you bought this, it might even be for you" and spoiling the fun of waiting for that wonderful day of Christmas) spoiled that I certainly will get this game this Christmas. I didn't even INTEND to see what I'd be getting this year, but freaking Amazon, as I said in those parantheses, spoiled it for me. I'll never use Amazon wishlists again.