Here's the thing. I'm not mad at GRRM for being slow at his job. He loses respect points because of that (compare to, say, S. Donaldson, who can put out much more complex (and I would argue, better) stories[1] in three year installments like clockwork, as he takes his craft much more seriously. But I can accept not everyone has the same work ethic). He's a slow writer. He does many other things (book tours, conventions, football, etc), and when he's doing those things, he doesn't write during that time. Well, fair enough. Those are the advantages of being your own boss. Good job if you can get it.
What irritates me about GRRM is his complete lack of regard for the fans of his series. He has said multiple times, the story goes to the grave with him. If he doesn't finish it, nobody will. That's a dick move. That is saying to the fans "I don't give a rat's ass whether or not you get to see the end of this tale. This is MY ball, and I'm taking it with me. Screw you guys, I'm going home". I'm sorry, but that is just effing lame.
Now, that's his right. It's his IP. But facing the same situation, R. Jordan made sure his fans would get to read the end of his tale, whether he got to write it or not. That's showing respect for your audience. I didn't love his series (it was far too derivative for my tastes, and moved far slower than I liked), but I totally respect him for ensuring the story would get finished if he didn't live to write it (which sadly he didn't). There is NO reason GRRM couldn't do the same if it came to it, except he's just being an ass.
In all honesty, I don't like him. I like his writing (mostly). And I'll pay him to read his books. But that's as far as it goes, a pure business relationship. As a person, I think he's a jerk, and a bit of a bully (not that I have any personal relationship with him, I can only go by the information he chooses to share with me). He doesn't care that I don't like him, and he can laugh at me all the way to the bank if he wants. That's fine.
I'm glad D&D are doing the HBO series for a lot of reasons, but one of the biggest ones is I highly suspect that series is going to give us the only ending we're ever going to get. It's not as good as if we got to read it (through no fault of D&D, they are limited by the medium they are using, and what they are doing with it is impressive, but it can't hold up to the written word), but at least it's something.
[1]as a side note about SRDonadlson's books, I'd love to see movies and/or a series done on them, they would be great (and there has been some interest in them both past and possibly present). Sadly, I suspect it's never going to happen, as the protagonist does a very evil thing early on in the series, something many would consider completely unforgivable, and probably rightly so (it would be barely watchable if an antagonist did it, but to have the main protagonist doing such a thing ruins any chance of the series ever seeing film). And it's not like you could cut it, because it's an act that deeply affects and drives him from that point on. Too bad really.