The latest book is taking a long time but should be finished. A graphic novel is also in the works.
I didn't love the way the most recent book was set entirely in Westeros (basically a very long book was split up geographically instead of chronologically) but overall I'm a big fan of the series. He really does a good job of keeping a lot of burning questions alive. Like: who is Coldhands and where is Benjen Stark?
The reason why I think this will translate well to the small screen is because they are absolutely serial novels, and HBO produces such great serial shows. The pacing in the books for when characters are broken away from and returned to will work well over the course of the season, IMO, if adapted well.