As a novelty item for a cat lover this is a lot of fun, but even though the puzzles do increase in difficulty as the book goes on, they are not at all challenging for anyone familiar with this type of logic puzzle, and inevitably there is a lot of repetition with the set up of the cat crimes - cats may be fiends but there is only so much they can achieve without opposable thumbs. All 75 puzzles are the table sort of logic puzzle without any variety... experienced puzzlers can do the puzzles without using the table to increase the difficulty level. It's probably a good intro to this sort of puzzle for cat lovers (adult and kids) who haven't done them before.