God, No! is a short read, and a much thinner book than my other choice, Christopher Hitchens' Arguably. I wanted some atheist reading material, however, and I think the Hitchens collection of essays might have served that purpose better.
Penn is very much an atheist, and the book does discuss the topic in some places, but if you're looking for something on the level of Harris or Silverman, you won't find it. God, No! is a great autobiography, full of honest and hilarious tales, but not magical, and nothing that would indicate whether the reader may or may not be an atheist as the full title suggests. Of course, being one who's enjoyed Penn and Teller since childhood, I realize this was probably the point.
I don't complain about language. You can say "fuck" as if it is the only word in your vocabulary for all I care, but I did get the feeling that Penn's vocabulary liberation on Bullshit! may have influenced his writing style just a tad. I love the word "fuck", but the profanity was seemingly forced according to my co-worker whom I let borrow the book. She did not like.
I did, though. I appreciated the honesty in the painful adventure with the hairdryer and could totally see something like that happening to me. I can relate his field trip to the bath house with my trips to the gay bars. Hey, when your gay best friend challenges your open-mindedness, how can you not accept the challenge? Both Penn and I didn't return from our outings as homosexuals, nor would we consider it a problem if we did.
Some people may be able to finish God, No! on a lunch break, but it doesn't diminish it's entertaining factor. Penn is, after all, an entertainer. His partnership with Teller has always seemed to be about being honest and showing people reality, and that there is no magic (only tricks), and doing so in a way that will make you laugh or cringe. This book epitomizes that experience very well.
As a book on atheism, or determining whether or not you might be an atheist, it likely won't do the job. As an autobiography, it get's a high score from me. I just need to figure out if I want to come up with a rating system of my own.