Seasons 1-4 were brilliant. Great stories and character development. Unfortunately as George R R Martin's writings faded out as the TV series over took the books. The writing became rushed, the stories weak and the series became about CGI over plot and sub plots. Season 5-7 were still pretty good, and I enjoyed watching them. However it obvious that the show had 2 different directions and the transition from George R R Martin's books to Dave and Dan's scripts was messy and disappointing. Season 8 in my opinion was fantastic to watch visually. Story wise and the characters were awful. Whole timelines of character development were ruined in a single episode. So many things were rushed and ruined. It's a shame such a world wide phenomenon ended so poorly.
I'm really looking forward to the spin off shows and what they will bring the the GoT universe.