He has to be ecstatic with the show so far. The Sword of Truth fantasy series, which is arguably just as good as Song of Ice and Fire, was made into a TV show and sucked ass. They changed too much, made it episodic, and made what was a heavy R rated series into a PG one.
This is by far the best fantasy adaptation for TV I've ever seen. It's not even remotely close. I remember when Martin announced he was in talks with HBO, I thought there was no way they could pull this off, HBO or not. Everytime I watch the show now, I'm just amazed. The casting is so spot on, the scripts are great and they are actually sticking to the books pretty heavily.
I'm just amazed it all came together so well, and I'm probably more amazed that mainstream folks are watching fantasy in record numbers.