Hard to say this is anything but a masterful adaptation of the books. IMO, the thing that has really made this for me is the casting. They have done an absolutely excellent job. My only minor (very very minor) nitpicks so far are:
I think Renly is miscast. I know he is a gayboy, but in the books, he is supposed to be the spitting image of Robert when he was younger. It seems like him and Loras are both bottoms and I think the book suggests Renly is a top.
Isn't Ghost supposed to be mute? I don't remember him barking or growling in the books.
In the scene where Ned calls our Cersei, they left out one cool part from the book. Cersei slaps Ned at one point to which Ned replies that "I'll wear it like a badge of honor." Throwing that back in her face was great.
All in all, great job all around. I love the opening too.