I honestly don't know what my game would be. There's still a lot of games I haven't played from this year, and I don't count HD (1.5) remixes, but as it stands, I'd probably go with New Leaf. Even six months after it's come out, it remains the only game I still try to play every day. Second place would be Etrian Odyssey IV (it's been a while since I've wanted to play any RPG enough to want to 100%; not even the SMT games can get me to do that).
As far as disappointments go, it'd definitely be Bioshock Infinite. The shooting was barely serviceable enough to get me through the game for what should've been the highlights of the game, which I found predictable and forgettable. The characterization was fine, but if you've looked into quantum physics as an from an educational standpoint, as either a math or physics major (especially the poor physics majors), you'd realize how heavy-handed and clumsy the plot was with its foreshadowing. I could NOT for the life of me understand how people thought the story was "mind-blowing."
You don't even need to be that educated. The plot holes were driving me up the wall and I don't know anything about anything.