Galapagos is a fun read, playful; for a book about the end of the world, it’s certainly more humorous and light-hearted than most, except perhaps Good Omens. The narration is fun — the narrator is pretty much a character, but also pretty much omniscient, so you get to know everything that’s going, but with opinions into the bargain.
When I think about it, though, I can’t find much substance in this. It’s very repetitive, and if there’s one single point that comes out of it strongly, it’s that humans have big brains and we cause our own problems, and maybe it would be better if we evolved to have smaller brains and less able to cause trouble. Which… sure, fine, but ~250 pages of story all focused around that begins to lose its charm.
Still, that’s what saves it — the charm, and the fact that the narrative reveals facts haphazardly, so you have to hang on to almost the last page to piece together exactly what happened throughout the book. It is charming, like I said, and very readable, but… Shrug?