To say I'm mad at him for being behind on the books would imply I particularly like the books. However long the new book takes to come out, I'll wait the extra year for the paperback.
However this kind of bullshit from creative types does piss me off. In many ways, I get his issues. Thanks to an adaption on TV his book series that he started 15 years prior suddenly became popular, and popular enough to be demanded by more than the Sci-fi/fantasy book club. He got caught in something he was unprepared for and neve got into the mindset that he might have to. This isn't like most manga to anime adaptations where one naturally seems to progress faster than the other, having the adaptation started well before there was enough material to make many episodes, or needing time bought due to sudden delays. This was someone that still feels he's allowed to go at his own pace even when a LOT of people are counting on him to do his part, and didn't even seem to punch it up 2 years ago when this outcome was starting to look like a probability and the jokes started coming out about how slow he was.
Even then, I'm not mad at him for that. Yeah, I'm pissed that I work payroll and I have to meet deadlines (having come in to do payroll with some rather serious flus over the years) while people like that can say "when I get around to it" with impunity, but not all jobs are important and time sensitive like mine. However, when deadlines are missed, show some fucking respect to your fans to own it. Say sorry. Give your reasons if applicable and not lame. Vow to do better in the future even if lying. You don't try to try and hide your own inability to meet a deadline by hiding behind adaptations never being exact. The show already went that path when characters were adults instead of teenagers and has had several additions and omissions already, so I don't see it as valid cover.
Martin can take all the time he wants with the books, but don't treat your readership / viewership with such disrespect that they should just wait on you to get your act together. You're already lucky enough to be in a position where this is possible (unlike say, if the writers of the show suddenly couldn't get an episode out for 2 months mid-season), don't be a primadona about it by avoiding the reality that you're letting people down, or acting like people that expect things from you are unreasonable.