The major flaw in his argument is his abject dismissal of personal experience. He gives all of about 2 sentences to the subject and fills the rest of the book with plausible sounding arguments that miss the point. He's either right or he's wrong, and no amount of logic changes that.

As people are intimidately related to mystical experience it makes for a rather weak read once you spot his refusal to examine cross-cultural accounts of experiences - especially if you're aware of the kundalini literature/have had experiences yourself (see my other comment).