I read the book several years ago, and just watched the show this weekend.
Both were really good in their own right. The big difference imo is that, while both balanced “snapshot of a fucked up town” and “murder mystery,” the show privileged the snapshot of the town and the book privileged the murder mystery aspect.
Personally, I preferred the book because of that. But the show was gorgeous and SO fun to watch, and every actress in there deserves a goddamn Emmy.