Man, I've watched Zardoz, I've read the novelization, and I still don't know what the deal is with it.
Watching the movie is difficult, both because it's an incomprehensible mess and because the mind naturally recoils from a seminaked Sean Connery. That's him on the cover of the book. He's wearing tiny pants held up by red suspenders. Do you know why he's wearing red suspenders? Because John Boorman doesn't hate us, that's why.
The introduction explains that John Boorman wrote the screenplay in novel form, then shot the movie in the hills near his home (because even coming of Deliverance he didn't have enough juice to get major studios interested). Then he had a friend help reshape the screenplay back into a novel. He doesn't mention it explicitly, but the clear implication is that everybody involved in the movie was exceedingly drugged up. I'd summarize the story, but it really doesn't make any sense. Likewise, I'd compare some scenes from the book and movie, but almost nothing matches up, so the only thing I could talk about would be how a scene would be incomprehensible in two different ways. I was hoping that the narrative voice would at least convey something of what was supposedly going on, but that does not turn out to be the case.