I almost wish that Martin had acknowledged he was going to be unable to finish the books earlier on, and dedicated himself to writing more on the television show. That way we could get a conclusion to the story, and some decent writing along with it.
Now we are left with a television show that is poorly written, and has so many plot holes that it's almost unwatchable. "Beyond the Wall" may be one of the worst television episodes I have ever seen. And although I was convinced that we would at least get "The Winds of Winter", I'm losing hope that we will even get that now. I still believe we will, but I feel like it is two or three years away. And to be totally honest at this point, the only thing I really care about is how Stannis Baratheon's arc finishes. Hopefully Winds will provide that.
The last two books definitely were not as good as the first three, but still had some good aspects. A Feast for Crows was good just for Cersei's point of view chapters, and getting to see just how crazy she is. A Dance for Dragon had the Reek/Theon chapters, which were so good I would actually skip other chapters just to continue reading them. Basically everything in the North in that book was good. Reek/Theon, Davos, Asha and Jon (Well, maybe not always Jon).