The first book is much better than the show’s first season. It also has many scenes that the producers of the show either rewrote entirely or truncated almost beyond recognition. The show is fun to watch but confusing at times and a lot of the details of the book are simply glossed over.
No spoilers here. Read the book and you’ll see what I mean. The show is much more of a costume drama with lots of gratuitous nudity and violence. Some major characters seem nicer or nastier in the show than they are in the book, rather they are complex in the book but rather one-sided in the show. I like both, but if I had to choose only one, I’d take the book.