Instruct: Classify Amazon reviews into positive or negative sentiment
Query: To call this a "book" is an overstatement

The book is based on a mind game, which I won't spoil here (out of respect for the reader, not for the benefit of the authors). However, don't be fooled by the 200-something page count. The authors use about 30-40 words per page, as if they are writing poetry, and the entire trick can be described in 10 pages maximum, including commentary. Granted, the game itself is neat and can be used as an icebreaker, but you don't need this so-called "book" to learn a tale that belongs in the public domain. Overall, this is a waste of money and shelf space.