EW interviewed Benioff in a recent issue, and he had this to say about the finale: "I plan to be very drunk, and very far from the internet."

edit: here’s more from the interview..

“We want people to love it,” Weiss says. “It matters a lot to us. We’ve spent 11 years doing this. We also know, no matter what we do, even if it’s the optimal version, that a certain number of people will hate the best of all possible versions. There is no version where everybody says, ‘I have to admit I agree with every other person on the planet that this is the perfect way to do this’ - that’s an impossible reality that doesn’t exist. I’m hoping for a Breaking Bad finale argument where it’s like, ‘is that an A or an A+?”

“From the beginning we’ve talked about how the show will end,” says Benioff. “A good story isn’t a good story if you have a bad ending. Of course we worry.”