Despite my disappointment with the show, the "official untold story" Fire Cannot Kill a Dragon, by James Hibbert, is a very good read. Granted, I have so far only skimmed, but the chapter entitled "The Forks in the Road" has some interesting comments about the difference between the books and the show:

BOOK SPOILERS INCLUDING A HUGE ONE

1. Even during the pilot reshoot, George realised the show "wasn't entirely my baby anymore"

”The director was talking to Dan and Dave. Nobody was saying , 'George, come over and tell us your opinion.' I didn't throw a tantrum or anything...I just came to the realization: I gave my baby up for adoption and now there is a parent teacher conference and I am not invited."

1. A grisly cited "example of the show's early autonomy" was when the producers decided to have Joffrey order a singer's tongue removed:

"George was none to pleased, because in the books Marillion ends up being a patsy for Lysa Arryn's murder..." Bryan Cogman said. "David and Dan's reasoning was it's better television to have this minstrel that we'd spend the season with and that we'd figure out Lysa's murder when we got to it, and we did."

1. Cogman explains that once they knew the show would catch up, "...it was learning a lot of these secrets and then in your mind figuring out, ‘What of that will work in the context of our show?’. George is then quoted as saying:

"It wasn't easy for me. I didn't want to give away my books. It's not easy to talk about the end of my books. Every character has a different end. I told them who would be on the Iron Throne and I told them some big twists like Hodor and "hold the door," and Stannis's decision to burn his daughter. We didn't get to everybody by any means. Especially the minor characters, who may have very different endings."

That's right - George said Stannis burns Shireen.

1. They then talk about blueprints and gardening and architecture etc, and eventually we get this explanation from Benioff about the changes:

"We don't get bonus points for being strictly faithful to the books. It doesn't give us anything extra. For every decision, if there's a fork in the road and the fork to the left is strictly adhering to the books and to the right is what's better for the series, we're always going to take that path to the right."

And this form Weiss about George stopping writing scripts and the show surpassing the books:

”We chose to see it as a great thing on both sides. There's this amazing world George has created, and now there are two different versions out there. There's no reason we can see why you can't be thrilled and surprised and dismayed by both of these two different versions of this world.”

1. And finally, from George:

”One thing David and Dan did really right, that I couldn't have done if I was a showrunner, is the vast majority of our Emmys are for below the ling - costuming, set decoration, stunt work and so on. They put together and incredible team of craftsman...[if I had put them together] would they have been the extraordinary people David and Dan found?”

There's doubtless more good stuff in here. But for anyone wondering, here's confirmation that the books and show are different things.

edited to link to the book.