My wife liked the look and sound of the game. The music is pretty nice. I don't get whatever the 'story' stuff is supposed to be communicating, though. There are these jigsaw puzzle paintings that you assemble as you go through the game collecting pieces, and they look like they have some significance, but if you're not the guy who created the game, you're pretty much left out of whatever it is. So yeah, it's a solid puzzle game, but I don't know what the hell it's about (other than solving puzzles for some abstract reason).
For the matter of value, well, that's a tough one. It's got excellent production values and interesting mechanics, but almost zero replay value. Once you've figured out all the puzzles (which took me maybe 5 hours total), there's not much left to do but theorize what it all means and try speed runs, if you're into that kind of thing. Still, there is something to be said for Braid as an experience. It's one of a kind, and for that I'll begrudgingly concede that there is $15 worth of something here, it's just not $15 worth of pure gameplay. Geometry Wars it is not.