Just finished Metro: Last Light, and I really enjoyed playing...
Witcher 2 (picked it a while ago on GOG for less than $5) very impressive graphics, nice story and a simple but good enough gameplay mechanics
Crysis 3 is a bit embarrassing for me to say that I wasn't skilled enough to be able to finished the story, but I'm enjoying the multiplayer a lot.
I also recently finished FarCry 3 liked it, other than the disappointing ending of the story I like that game.. Also the multiplayer is surprisingly solid!
Mirror's edge is a game I keep playing again and again (mostly for speedrunning) but I'm also excited for it's upcoming sequel..
Portal 2 is also a great game (one of my all time favorites) with absolutely brilliant script, continues the awesome and innovative gameplay of the first portal with a great story and a lot of great humor (gotta love weatley).
Also, I picked up the newest tomb raider in the latest steam sale (I skipped that game the last time it was on sale), I like it, but not that much (I have a thing against 3rd person games in general).
I'm waiting for a good sale on assassin's creed black flag, maybe thief, and natural selection as well.. Hopefully we will see another large steam sale this christmas..
What games are you planning to pickup in the next steam sale?