Thought I'd put it here, even though I have it on 360, since the first game was released on PC and this seems to be more of a multi-platform section than the rest
In short; GET IT! The puzzles are fun, some had me stumped for a while but the main pull of the game is the outstanding narrative. The story is pure win, GLaDOS is as funny and mean as ever and then there's Steven Merchant-bot (Wheatley) who's basically Steven Merchant as an AI and a bit thick. Not to mention the coop section is very well made and a lot of fun with a friend.
Sadly there's no mention of cake or any other dessert for that matter