Expect a fair amount of out-of-proportion fanboi rage over this series. But as I've argued before, a movie or TV show is an entirely different art form than a book, and it's silly to expect to get from one everything you got from the other. I hear good things about the producers of this HBO miniseries from a friend who knows them, and I think the cast looks good. I suspect the series will be awesome in a way that is completely distinct from the way the books are awesome, probably preserving only outlines of character, plot, theme, and tone — just as both the book and the movie L.A. Confidential are great, but in utterly different ways.
I still think Patrick Stewart would make a great Stannis, and that Brian Blessed would be perfect as Robert if he weren't getting a bit too old for the part.