Bought this on a Steam sale recently and I don't regret it at all. Worth the normal price too imho, but I would probably not known about it if not for the sale, just saying (I didn't know about the demo then).
I'm only 2 hours in the game so I'm not finished yet. But so far I find it an excellent little puzzle, with some physics rules that changes a bit during gameplay to keep it interesting. Also kind of like LIMBO as mentioned before. Neat little game!