The Damnedest Thing was always going to be a tough act to follow. Granted, a lot of the 'take no prisoners', muddy, bloody pursuit of truth themes find their way into this book, but at the same time, McKenna introduces a parallel.
He rather grandiosely claims to be the only person ever to have properly understood Moby Dick, Melville's sprawling classic. Agreed, there is a compelling case to be made regarding the whiteness of the whale, the wildness of the sea, and the singlemindedness of Ahab.
However, it is just as plausible - in fact, far more likely - that Moby Dick is Melville's fledgling attempt at coming out of the closet and dealing with his feelings for his friend, Nathaniel Hawthorne. Indeed, the later, strongly homo-erotic themes of works like Billy Budd should lend a clue to this.
So, overall, not a bad book. However, it spends too long barking up the wrong tree to be a proper addition to the spiritual lexicon.