Put this in the other thread, but want to update my previous call here too. I'd originally gone for Legend of Grimrock, which was pretty good but was almost chosen by default due to me not having played any other 2012 releases.
Now that I'm almost finished with Dishonored I feel there's a proper contender that really deserves the title. I actually Dishonored would have been my GOTY for most of the past few years.
+ Wonderfully crafted world with stunning art direction and excellent attention to detail
+ Story and lore of the world are really well fleshed out
+ Open environments and multiple approaches to objectives
+ Fun powers
- Stealth mechanics aren't that great
- Really demands two playthroughs due to the way chaos is handled (not sure if this is a negative, but I've not used most of the powers due to trying to play with low chaos and kind of feel I missed out)