But you can't sustain that kind of intensity with the 4th book.
The 4th book might be my favorite. While I agree that it isn't as intense as the previous three, I feel like Westeros, as a place, is more interesting in it. It's at a complete decay of the peace and values it had after Robert's Rebellion, and the land is hurting. Brienne's Big Adventure through the middle of it shows a society that is barely hanging on, with the population turning to religion and poverty with the Sparrows. The big POVs for the 4th book are Brienne/Jaime/Cersei (basically one set of characters sharing a single story arc), Dorne's stuff (which was building towards Daenerys foothold into Westeros), and a little bit of Sansa/Arya/Iron Isles.
I haven't seen the tv series, and don't want to, so I don't know how much of this stuff has already played out for other people. But I think the "love triangle" (if you will) of Brienne, Jaime, and Cersei is narratively fascinating. Jaime is looking for redemption (he's coming to terms with being an honorable man, despite having grown up surrounded by Lannister pragmatism, and he sees salvation in Brienne's sense of justice). Brienne is looking for justice in an unjust world (leading her to Lady Stoneheart - I know she's not in the tv show, which is weird, because her forgiveness, which won't be easily given, is where Jaime will find the peace of mind he's looking for), and Cersei is paying the price for basically destroying Westeros with her own greed - her story is going to be a tragedy, almost assuredly, but it's forcing her to rock bottom so she can have a moment of redemption.
Anyway, for me, the 4th book has some of my favorite character moments in the series, and focuses largely on the characters that I like the most. The 5th book suffers a bit from not actually being in Westeros for most of it, so it feels like the stakes are somewhat far removed from the rest of the series, but it moves some important pieces around the board, setting up the next book. I really think the 4th and 5th book get a bad rap. They are not the same kind of story as the first 3, and I think the expectations of having to wait a decade for each book really makes people want them to be something more explosive than they end up being, but there's good stuff in there. I've only read the 5th book once so far, and it is easily my least favorite of the bunch, so I'm curious if rereading when Winter has a release date will improve my opinion of it.
Its pretty clear he wrote himself into a wall.
Oh, I disagree. It's pretty obvious where he is going. But knowing where you are going and actually getting there is two very different things. One of the things I like about the series is how complicated it is (over a thousand named characters!) and moving a character from point A to point B while also making it an interesting story unto itself can be a challenge. I feel like the final book will go much faster because the difficulty is in setting up the dominoes, not knocking them down. But, of course, this is George R. R. Martin, who would take 3 years to write a birthday card.