Game of Thrones died during the Season 4 finale. The show was only good because of how it was mirroring the incredible book series. There were always differences but the last straw was setting Tyrion on a different path. After killing Tywin in the books, he becomes incredibly bitter and Jamie reveals something major about his past. Tyrion then becomes so filled with hate and swears to kill Jamie and Cersei. BUT IN THE SHOW, the two brothers share a loving goodbye. This sets the show on the path of sterilization that separated it from the books too much. Tyrion was supposed to become vile and vengeful but in the show he just becomes empty in emotion and wit.
I haven't finished A Dance With Dragons yet, but I could tell before I even reached the halfway mark that the story in the show was long dead by season 8. Why they chose to cut Aegon/Young Griff and Griff/Jon Connington I do not know. It was such a big mistake