I've been rewatching Game of Thrones lately, and more and more I'm certain that Benioff and Weiss have been unfairly pilloried for the decline of the series after Season Four.
In the prevailing zeitgeist of GoT fans, George RR Martin can do no wrong, and the TV producers failed to live up to his vision. My counterhypothesis is that Martin is a sloppy and self-indulgent writer who created a bunch of pointless subplots that contributed nothing to the main plot and left them hanging. Benioff and Weiss actually did an admirable job of salvaging what they could from all the pointless subplots and weaving them together into a more-or-less coherent whole.\
I was a big fan of George Martin's short stories. I don't know if I read any of his novels before GoT; if I did, they made little impression on me. GoT began quite impressively, but by the third book it became obvious that he enjoyed creating new stories more than finishing them. Long before I saw the TV series, I was getting annoyed with the proliferation of subplots that didn't seem to be contributing anything to the greater whole. I don't know why Dance of Dragons was nominated for a Hugo; it seemed to me to be the weakest book in the series.
Anyway, as I rewatch GoT, I'm enjoying it more. Some of the plot holes are annoying, but overall I'm more impressed on my second trip through. Having shed the idea that deviating from the books is always bad, I'm really enjoying what they've done with it.