Crying shame nobody else picked up on this. It's really good, and has a stupid amount of secrets in it. I don't really want to say too much about it, but the puzzles are great and if you're into puzzles and rooting about using skills you have gained over the course of a game for secrets, you'll have a great time here.
Combat gets better as the game goes on, it's still not amazing by any standards, but it's not the reason to play this game.
It's criminally overlooked, I've always seen it in my library but never really pushed myself to play it until now, but I am glad I did.