I've played this before, but last time I guess I just wasnt in the mood for that type of game since I quit somewhere in the ruins. Started playing it again yesterday and got totally hooked. It reminds me a lot of Zelda , similar sort of puzzles (the jumping bits are annoying, especially the timed ones but not enough to make me throw down the pad yet). Since it's the hoildays (and people wont stop bloody calling or visiting) its good to have something that you can just drop at moments notice.
If I enjoy it this much to the end I'll definately be getting the second one.
Calling it an FPS seems wrong since it's so much more than that.