The first two seasons pretty much plays scene for scene how the book is written (chapter to chapter).I love the GOT books, but I never watch TV so rarely see the show. I tend to get most of my show viewing outside airplanes just watching a few clips on youtube. Low-key pissed that I am bound to get the books spoiled by the show. Those things are massive, quite an investment in my time. I remember how angrysad I was that the author of the Wheel of Time series died 11 books into a 14-book series - by that stage I had to know how it ended.
I just hope he follows through on his threats that the last book is a 1400page explanation of snow blowing across graves.