“A fun illustration of something,” is pretty much as far as the book goes: it hints at grand unifying patterns, but the pattern it finds is just the abstract notion of self-reference, and then it keeps bringing it up, making a few unnecessary references, showing some pictures, and asking, “Isn’t that cool? Isn’t that weird?”
The book is a puzzle. That's it. It's not the answer to life, the universe, and everything. It's a nice puzzle that illustrates how self-referential things relate to one another. Superficially. I'm okay with that.
Because it's a fun little puzzle, it engages people's minds in new ways. This is what has caused all of the praise over the years, not because it's some post-grad-level deep-dive into epistemology or something. I think the reviewer misses the point. The criticisms they make are actually features.
I could criticize the book as well. I struggled with it. But I wouldn't criticize it along these lines. They don't look very insightful.