I think that there's useful advice in this book, but there's quite a bit to not only think about and apply, but practice. The general idea is that as a performer, one identifies patterns and attitudes in spectators and then adapts the performance and execution of an effect to create a stronger emotional connection and increase your skills of persuasion.
At a basic level, I feel that most successful magicians already accomplish this to a certain degree. And, on the other hand, those magicians that don't connect with spectators generally lack this ability. In my opinion, the ability to truly connect with spectators - virtually any spectator - is what separates a successful and good magician from the many that simply execute tricks.
The book categorizes spectators and identifies and describes their traits. And the book encourages you to practice various techniques to better your observation skills, alter your behaviors and ultimately improve your magic. I found the book fascinating and worthwhile reading. And I may make observations at upcoming gigs to test some of the concepts. I can't comment on the long term benefits as I am just starting on this road. But I think this easy read contains some useful ideas.