I've always enjoyed Penn and Teller's shows, and I am a fan of their "Bullshit!" program on Showtime, so I expected to be entertained by Penn Jillette, a self-described atheist.
As I got into the book I realized that atheism was just a loosely tied thread through the essays, but the book was more of a collection of entertainment tales (Sigfried & Roy, David Copperfield, etc.), which were only mildly funny.
Penn also describes himself as an "asshole," and I have no argument with him there. By the end of the book, it became more of a rambling libertarian screed ("let everyone take guns and knives on to airplanes..");and I hurriedly finished the book, so that I could read something by someone not so proud of being a loud, brash asshole.