The 2 DLC are for after beating the game, or at least when you get close to the ending. They add to the story after the ending of the game. And yes, they're meaty in terms of gameplay, not by a lot though.
If you really like the game by the end, they are be worth it, if not, just watch a walkthrough to get story bits out of it.
[img:91f1fb12c3 ]http://i.imgur.com/fTzqMvq.gif[/img]
