While the writing and storyline throughout season 8 was sub-par, abysmal even and i would give it a rating of close to zero, the last episode was actually really good. All was tied together well. I gave it an 8. To me it had a similar feel as the first few seasons - more story, it flowed with greater authenticity and had less shock for its own sake.
However, I suspect there would've been a lot of GRRM input into the last episode in the way that there would have been extensive discussions on how the story was to end. So well done.