I found the first half of this book a bit dull and frustrating. Dull because it was mostly worldbuilding and (admittedly beautiful) description, with not much forward movement. Frustrating because the narrator didn’t seem believable to me—a bit too sanguine, trusting, and passive, given how obvious it was right from the start that he’d been duped. I also find it annoying when writers associate the identity of ‘scientist’ with the tendency to give needlessly precise, dry descriptions, e.g. “He is approximately 1.88 meters tall and, like me, of a slender build.” And when they’re shown to be describing all their thoughts as “hypotheses”, and all the information they encounter as “evidence”. Come on, scientists don’t talk like that!
That being said, when the plot started to pick up about halfway through, I got really into it. If it’s ever adapted as a film, I will very much look forward to watching it. I think my reading was enhanced by having read the Chronicles of Narnia—arguably this book takes place in the same fictional universe—as well as The Ocean at the End of the Lane and The Library of Babel. If you’ve enjoyed any of those stories, I expect you’ll like this one.