The series definitely is going to be ahead of the books, and it also goes off in some other ways, but they are all okay with George R.R. Martin, who works with the series' producers and approves of what they have done with his world.
I have to say how happy it makes me to see George R.R. Martin enjoying his huge success and fame. He was successful for aeons before, but he is at a whole new level with the TV series being so big, and he enjoys it so much and is also so generous with giving credit to the producers (whereas so many other authors are not okay with their work being changed in any way). I was in particular tickled when he was on a "gay of Thrones" ("gay of Thrones" is a video recapping done of the show, from the perspective of a gay hairdresser in Hollywood named Jonathan, very funny for GOT fans).