If it were not for the puzzling...
The atmosphere and the whole feeling to it when listening to the music and reading all the texts (which you should since it makes you more involved in the story) that is to be found every here and there gives the experience a mature and philosophic touch, which to me is very refreshing in the world of video gaming.
If they would have made the movement more free (instead of the move-from-spot-to-spot), and the puzzling less frustrating, and perhaps added a couple of chapters, this would have been awesome.