Good, but not as great as it could be.
Overall, I had fun playing through the different puzzles. I went ahead and purchased the game after playing through the demo assuming that the puzzles would get significantly harder by the end. However, though most are still enjoyable, the puzzles are generally too easy and more appropriate for a younger crowd. It usually took 2 minutes or less to get through each puzzle, and I breezed through the game in a mere 2 nights of gameplay (without staying up all night to do it).
I enjoyed the room games where the player is required to find and properly use various items found around the room, but found that the hints gave too much away to really make it very challenging to figure out what to do.
If you enjoy challenging puzzles that really make you think, this is probably not the game for you (though the sound and graphics are done quite well.) I remember doing puzzles out of a book when I was a kid, and I think that this game would be really fun to the right 10-12 year old.