This season Martin (and maybe last season as well?) did not write one of the episodes. He's also supposedly ditching all other side projects to buckle down and finish the book.

His blogpost on that whole thing (it's clean for show readers for the most part, then he clearly marks the section with book spoilers if you don't want to read those)

http://grrm.livejournal.com/465247.html

As for the show, Benioff and Weiss know the broad strokes and major plot points, but they don't have all the little stuff in between. The show is going to hit 8 seasons for sure, but without the books there's talk the last two seasons are going to be shorter (like how Breaking Bad split the last season into two parts).

Sucks, but this is what we get when Martin takes his sweet ass time working on everything else BUT the books.