This is perhaps the BEST line-up I've seen. I own each of these games and every one of them has provided hours of fun.
Bastion is absolutely dazzling. The story is great, the graphics are astounding, the way the narration takes place is better than any game of this style I have ever played. I highly recommend this bundle for this game alone.
Limbo is a great puzzle game (much like Vessel). Again, hours of fun and an interesting storyline.
Amnesia is a great game if you play it like intended. Set it up in a dark room, setup the brightness just right, and turn the speakers up. It is a creepy little game.
Psychonauts and Superbrothers are both good games as well. I bought psychonauts through GOG.com during a special that lanux showed me a few years back.
Overall, this is perhaps the best bundle that HIB has put out. Highly recommended!