An excellent game all round. I was very confused at first but after a while got my bearings and I found it a lot of fun. Nice simple music that gives the game a dark feel. I also appreciate not having to pick up any items - in these games it can sometimes be almost unavoidable you'll use a walkthrough and find you've missed some object tucked away somewhere, but here you can just concentrate on the puzzles.
Sorry for the short review, but I think the game works when you know as little about it as possible before you start and find your own way. Enjoy, and try to avoid using walkthroughs - the puzzles aren't THAT hard, you just need to be methodical.