Well The Witcher 2 was the biggest surprise for me this year.
Unfortunately there were some disappointments this year though.
AC:Revolutions was fun and good for a rental but no way a GOTY
Arkham City was great but didn't have the impact I thought it would, I guess living up to Asylum was a hard feat. Also the Catwoman pass code bullshit left a bitter taste in my mouth.
Uncharted 3 was disappointing in certain ways, it kinda just took U2 and continued the story, no innovation of the terrible controls/AI. Not a bad game though by any means.
Saint's Row 3 had huge issues for me on PC, it took me ages to download even though I had the discs, then when I got it installed the sound didn't work at all. Additionally, day 1 DLC can get fucked. Yes you should lose scores for that.
BF3/MW3 are just retreads. I have mw3 and it's fun to mess around with on with mates, but fundamentally not that different from MW2, and not a goty.
Deus Ex was fun but sometimes a bit too boring and monotonous.
I haven't played Skyrim, but I doubt i'd consider it if it's anything like Oblivion or Fallout 3/New Vegas.
Dragon Age 2 is an affront to the gods and should be deleted from public memory.
For me it's a toss-up between The Witcher 2, Portal 2 and Infamous 2. Leaning toward The Witcher 2, possibly because it was the only playable WRPG this year, and because it was a great game.