They bit off more than they could chew...
There is a lot of backlash regarding the trajectory the show has been taking since the end of source material. I believe it's apparent to most viewers who take an objective glance that the show has been steadily declining in quality since season 5.
Who do we blame here? GRRM for perhaps leading D&D on, making them believe that he will either supply them with infinite source material, or will finish the books before the show passes the books.
Or do we blame D&D for biting off more than they could chew? I firmly believe the show was created on too large a scale to truly finish in a competent manner without the original writer at the helm.
The production values are top notch. The visuals are incredible. The costume design is phenomenal. I will certainly await every episode with eagerness, but sadly the narrative has suffered greatly and so has plot consistency. This makes the show a fraction of what it was in the earlier seasons.
Perhaps with GRRM at the helm for the final two episodes, we can at least have an incredible conclusion.