I enjoyed this book, but with a few qualifications.
To start, the book should perhaps be titled, "Some of the Weird Things People Believe," since the book doesn't really get into *why* people believe the things they do. With that caveat, I did enjoy the book for the most part.
The author's central premise is to apply scientific or logical reasoning to some of the more well-known fringe beliefs in the US/Europe. If a fringe belief system calls itself scientific or uses the discourse of science/logic, Shermer's belief is that they should be open to being evaluated with the same measuring stick.
He makes a big point that he's not trying to poke any holes in religious belief or faith. Rather, he underlines (several times) that religion and faith have nothing to do with science and reason, and that one can happily enjoy both logic and faith.
The first section of the book is a good nutshell introduction to logical and scientific reasoning, with some tidbits of the history of scientific inquiry thrown in.
The second section deals with creationism, or more specifically, "creation science." Shermer makes another big point that he doesn't have any bones to pick with creation beliefs. In fact, he outlines several other belief systems in the world with a similar creation myth to that of Christians. His problem is with "creation scientists," those who purport to use science and the scientific method to position their religious beliefs in the scientific community.
The third section of the book deals with Holocaust deniers. I found this fascinating, since I didn't realize this really existed. Again, because the deniers use the discourse of historical, logical inquiry, Shermer felt that they should be subject to an evaluation based on the same principles.
Other sections in the book include an analysis Ayn Rand and the cult of objectivism and fortunetellers/psychics.
Clearly, Shermer's expertise is in creationism and Holocaust denial. These two sections occupy 2/3 of the book. And this is one of the weak points, I think. The other chapters are tacked on, almost as afterthoughts by a publisher who thought that the creationism/deniers weren't enough for a book on their own. I also suspect publishers in the unfortunate title.
Shermer knows a lot about creation "science" and Holocaust denial, as well as the actual scientific facts about the origins of human life, and the Holocaust. Those two sections are the most compelling of the book, since his expertise comes out strongly.
Though it's beyond control of the author, the printing and publishing is also sub-par.