My take on the quality of the show is this:
The first four seasons were fantastic political drama with fantasy elements. This is how the show made its name. Lots of intrigue, great world-building, great dialogue, shocking twists.
Seasons 5 and 6 totally lost their way, and were dull and boring, both from the political perspective and the fantasy/action perspective. Even though the story was halfway through they were still introducing new elements like Dorne that only obstructed the final goal of the narrative without actually reintroducing any of the interesting politics of the early season.
Therefore the showrunners said 'Fuck it, we need to wrap this up' and decided to pivot to full-scale fanservice fantasy schlock in a race to the end to get it over with. It's not a terrible decision given that they were clearly out of interesting political material and they absolutely had to deal with zombies and dragons eventually. It's more fun to watch than Seasons 5 and 6, it's just not the same show at all as the one everyone loved over the course of the first 4 seasons. But at least it's watchable, and at least it's clearly going to end with a proper resolution.