If you enjoy puzzles which carefully interweave illustration and prose, this is a good pick. The puzzle is challenging enough not to be boring, but it's not mind-numbingly hard like some others (notably Christopher Manson's "Maze," the only book of this genre I've liked better than this one). The illustrations are beautiful, and the aura of enigma created by the puzzle enticing. The only drawback I would cite is that once you make a certain intuitive leap in the puzzle's trickery, a bit of busy work lies before you to finish. But reaching that leap is reward enough. A good pick, if you can track it down.