This was Scott Adams' first non-Dilbert book. If you're used to reading Adams go on about Induhviduals and stupid managers, or if you've never read Adams trying / pretending to sound philosophical in one of his books, then this isn't what you'd expect.
Adams describes it as a "thought experiment" of sorts, one where he tries to provide some sort of explanation for basically life, the universe and everything. Although it's a work of fiction, it sounds like Adams is trying to see how people will react to his form of philosophy — it seems to be one of his favorite things to do something just to provoke reactions. (Yeah, he and I are alike that way.)
Adams starts from simple assumptions about the nature of God, and the nature of probability, and proceeds to try to explain everything from gravity to string theory to psychics to women. Yeah, women. You'd think a guy would know better.
It's a thought-provoking read, as long you keep some of the skepticism down. Adams himself acknowledges that some parts of his book are just plain-old creative BS trying to pass itself off as something deeper. Smart people would appreciate it as quick and light-philosophical reading, but I don't think it would survive serious logical scrutiny.
That being said, it's definitely worth the read, if only to get inside the head of a popular cartoonist. I think this part of Scott Adams is the part that writes all those garbageman strips. =p