I will say again: the show is working from bad source material at this point. You stanleys can deny it all you want- PD can claim that AffC has the best actual writing in the series, blah blah blah, Walrus can do his "is he blatantly trolling or actually this mindfuckingly stupid" act all he wants, but the fact is that the narratives of the book series went to crap in the last two books, and I don't see that improving going forward either. It's pretty simple to figure out why, too: GURM has become increasingly interested in world building and decreasingly interested in story telling. Look at what he's put his energy into post ASoS. The book series could have been a story about mankind's petty political squabbles, or how mankind came together to stave off a terrifying ice zombie army, or how dragons came back to the world, blah blah blah. It still may, but it's obvious that for GURM, world building is more important than telling a story. World building in service of narrative is great, but that's not what we've had here. GURM has been running around like dumb, hyperactive kid that just wants to live in that world instead of tell a coherent story.
Now, as for the show: D&D really do kind of suck. They're kinda dumb. When the show stuck more or less to the narratives of the first three well written books, they didn't do too much damage other than "let's shoehorn a shit ton of boobs in." When the narrative became OVERLY bloated in the last two books is when they had to make choices, and those choices have mostly been poor and missed the mark of what made the earlier shit great. For every Hardhome, we've endured like 3 stupid rape plots. I assume that major plot points we haven't gotten to in the books are mostly consistent with what's been shown on the show: I expect Stannis's army to get butchered early in the books, and for Stannis to die. I don't think Brienne will be the one who does it, but whatever- largely it will be consistent. Some stuff like what happened at the end of ADWD in King's Landing will probably play out differently on the show, but again- I expect them to hit the major storytelling beats of the books going forward.
But, let's stop kidding ourselves and be honest. This is not 36 Chambers or even Wu Tang Forever era quality. We're drifting steadily downward into The W and Iron Flag territory here. Take off your fanboy blinders and deal.