I read the first one and about 150 pages of the second one. The first one is an interesting story that is not told well, if that makes any sense. Like, if someone tried to give you a synopsis of the book, you'd say that sounds great, but when you go to read it, the prose is pretty lifeless and it is extremely longwinded. The second book is translated by a different person, and that person's style is even worse, so I couldn't continue.
So it's a draw: read the book if you want to understand all the things they are glossing over, but watch the show if you want whatever details do remain to be exciting.