I'll pitch in:
Best:
1. Batman: Arkham City
2. Deus Ex: Human Revolution
3. Sonic Generations
4. Crysis 2
5. Portal 2
Skyrim/The Witcher 2 get disqualified because I haven't managed to finish the damn things yet, though they're certainly great games.
EDIT: Honorable mentions for Kirby's Return to Dreamland, Alice: Madness Returns, and Trine 2.
Worst:
5. Brink - I wouldn't say it's bad, more that it evoked a "meh" response from me when I actually got to play it, because I had not known it would be a strictly competitive multi-player shooter with a quite literal throw-away campaign. It was rather unpolished on release, as well.
4. Rage - I'm sure it's a fun game, but I couldn't get past all of the issues the PC version had, it annoyed and infuriated me, causing me to declare it as a waste of 24 GB.
3. The First Templar - Poor AI, poor combat, missing animations, low quality detail and dusty look overall made what could've been a promising game just be forgettable.
I'll simply go on hearsay for the last two spots as those are really the only "bad" games I can think of that I've played which were released this year.
2. Duke Nukem Forever - I believe it got a worse reception than it deserved simply due to its reputation and that people are ignorant of its actual development cycle and the fact that Gearbox essentially Frankenstein's Monster'd a completely new game together from the remains of 3D Realms' in the space of a year and a half or so. I'm not really sure if this should take "The First Templar"'s spot, honestly, simply because I was interested but all of the negative press after it was released made me decide to avoid it.
1. Call of Juarez: The Cartel - I'm not even going to say anything myself, merely provide some links:
http://penny-arcade.com/patv/episode/call-of-juarez-the-cartel
http://www.escapistmagazine.com/videos/view/unskippable/4884-Call-of-Juarez-The-Cartel-Part-1
http://www.escapistmagazine.com/videos/view/unskippable/4933-Call-of-Juarez-The-Cartel-Part-2