>>132931911The first season is a pretty close adaptation of the stories it contains (all of book 1, parts of books 3 and 5) but season 2 is a terrible adaptation (Endless 8 is literally 8 times as long as it was in the novels, and as such, the other things it adapts, book 2 and parts of book 6, feel rushed af). Disappearance is a literally perfect adaptation of book 4.
Overall, I'd say that if you prefer to see things in prose rather than animation, the books are a good read, but if you're not that bothered, books 1, 3 and 4 aren't really worth it since you've already seen near second-by-second adaptations of them.