Tons of great answers in this thread, but as you can see from my username, The Expanse is my favorite piece of media of all time. Both the books and TV show are god tier IMO. The show is one of the rare examples where the majority of the book readers agree that the show is a top tier adaptation, as opposed to a lot of other shows based off great books that the book readers don't like due to major changes. There are definitely changes to make the show flow better, but I'd say the changes are very well done and I've gone through all the books and novellas twice, and watched the show about 8 times all the way through.
Both the books and TV show are top tier sci-fi. Any sci-fi fan owes it to themselves to give either or both a shot!