My conclusions are twofold. First: yes, this pair of books could have been shorter. 1200 pages, maybe. I'm all for dense storytelling with lots of underhanded clues -- Rothfuss is doing a great job of that these days -- and Martin does enjoy planting his clues and symbols. But I'm pretty sure he doesn't have so much underhanded information that he needed this much surface to hide beneath. A prophecy here, a dream there, a damnably brilliant aside about ravens elsewhere -- you keep it moving forward.
But second: if you asked me to swear that books 4 and 5 were too long, I would mumble and wave my hands and then point at the Winged Monkey of Samothrace. Because at no point was I bored, tired, or in a hurry to get on with it. Every piece of story, every viewpoint character, I wanted to know what happened next. If Martin does this for another 1600 pages, and it's not over yet, I will read the books and be happy because they're just good reading.
(Maybe I should hope he's not reading this review.)
I can remember thinking (back in 2005) that book 4 was bloated with unnecessary scenes. ("I felt like a lot of time got marked," I wrote.) But that was half a book, and it works better in completion. The focus -- if I can use that word unironically -- the focus of book 5 is the twinned struggle of Jon and Dany to rule their newly-acquired realms, the Wall and Slaver's Bay. But this is really a triple struggle; it goes back to Cersei at King's Landing, which took up so much of book 4. That is why we needed her viewpoint, small-minded and blinkered as it was. All three of them are making a hash of it, but in different ways.
(It's interesting that Tyrion is not involved in that command storyline at all. I have always felt that, amid all the POVs, the three protagonists are Jon, Dany, and Tyrion. But Tyrion is absent from book 4 and essentially passive throughout book 5; Martin literally turns him into comic relief. I'm sure that's just a matter of focus -- Tyrion danced all over the early books, and he'll be back on stage -- but he started out with the people skills that Jon and Dany lack. I mean, aside from the skill of knowing when to not flip out and murder people.)
So time passes, stuff happens, and the pieces move around the board. You might expect more movement, but only if you don't acknowledge that trying and failing (and flailing) is a movement, in story terms. Both Jon and Dany will certainly be in new situations next book -- Martin isn't being subtle about that -- and where will Tyrion turn up? I have no idea. But I am still along for the ride.