I already have Rochard, Shattered and SPAZ. I got them all during various Steam sales. I enjoyed Rochard. It wasn't very hard, and the puzzles were quite easy, but I want to play through again and find the two hidden places I missed. Shattered is a good time waster game if you just need to kill some time and don't want to get into something complicated. I really like SPAZ. It's the kind of game you think you're just going to play a bit of, then you just can't stop.
The only game on there I have interest in is Vessel. I was hoping to get it during a Steam sale. I think it came up as a flash sale during the Summer sale. I guess I might as well toss in $5 for the bundle just for Vessel since that's probably what it would go on sale for anyway.