Dragon Age 2. What a fucking unmitigated disaster. Though in a year or so, I think Bioware as a whole may wind up being the popular retrospective FOTY for 2011. Dragon Age 2 kick started a rather poor year for them, what with the studio becoming an abused brand to sell traditionally non-Bioware games (like C&C), losing recognition as a great studio (I believe there was some list which they were pretty high up the year before, and this year have sank dozens of places) and the disaster that is TOR (as a game -- I don't care to comment on how successful [or not] it will be commercially). Whilst neither of those two are as bad as DA2, it certainly set the tone for the rest of the year for them.
At least with Skyrim PS3 there's a great game behind the awful issues, and I'm sure the folks that made the game are pretty bummed that their hard work on the game design, improvements from Oblivion and the world they crafted and so on, has been undone by these issues. Criticism is certainly due, but I think Bethesda released it on PS3 in good faith, even if their testing was so obviously lacking.
On the contrary, Dragon Age 2 was simply shat out, and Bioware have shown very little remorse for it, instead opting to blame the fans for not getting it, or whatever. So that gets my vote.