ADWD was one thousand pages and the majority of it was great, and the entire Theon plot was the best writing GRRM has ever done. Nonsense hyperbole that the entire book was bad doesn't make for a good discussion because it's just not true, unless you've always hated GRRM's writing.
Theon's chapters were fantastic. Bran's and Davos's were good too. The rest of it really made me question why I still read this series.
The 3 primary ASOIAF characters - Jon, Dany, and Tyrion - have some of the most plodding arcs I've seen in recent fantasy series. It is on par with the middle Wheel of Time books, where it feels like there was no sense of purpose in where GRRM was taking the story. The same things he took 10+ chapters to tell for each of the characters in AFFC/ADWD could have been done in 3-4 chapters in the first three books.
I also got the feeling that he was just adding things without have any sense of how it was going to go down. The Greyjoys, Martells, Aegon, etc are characters I personally find either completely flat (Arianne) or caroony (Euron). So far, with what we know of TWOW, there's no indication that things will improve. And while Martin's writing is easy to read, it's not some stellar prose that makes keeps me invested even as the pacing is slowed to a crawl with no interesting developments.
I loved ASOIAF and, when I read the first three books several years back, I thought this was by far the greatest series I'd ever read. Then Feast came out, followed by Dance, and it has fallen considerably imo. I'm still astounded by how opinions on them have changed to them being accepted more in the last 5 years or so. Many works of fantasy are better, and I personally think the show adaptation is stonger than the books.