The books are a fantastic read.
The first four seasons of the show are awesome, then from season 5 onwards it slowly starts to tail off story wise as the show writers began to outpace the source material.
The production values and big special effects laden battles cover for the drop off to some degree, but by season 8 there's a lot of garbage level writing on display and you can tell that Benioff and Weiss (show creators) were rushing to finish the show as they were rumoured to be in the running to take on a major Star Wars project.
After the disastrous ratings for season 8, that didn't happen.