This book is a very easy, fast read. Since it's clear that Gene and his co-author (Julie McCarron) had done their homework, I wish they had included their sources, because I'd love to be able to cite some of the information that was included. Since they chose to omit references, that leaves it an entertaining book, but unfortunately not one that can be used credibly in serious discussions on the topic.
I understand that he wrote this to reach the widest audience possible, but I think it could have easily been written at higher than a third-grade reading level: as most people have graduated high school these days, if not attended at least some college.
Overall, this is still a very beautifully-produced and enjoyable book.