You can see GRRM was hands-on involved... With such amazing attention to details, and more Easter eggs for fans of the original series than dragon eggs!
They didn't try re-invent the wheel, or create a different Westeros... but, you can see the vast improvement, giving the fans more of what they want and what they loved... Somehow made the sets even more true to the books... like the iron-throne actually looks closer to what the books described, while still being a plausible earlier version to what we see later in Game of Thrones.
And, with this story, the literature that it's based on is a complete... so, show-runners going and doing what they want, the story is there and in place.
I have lot's of hope for the series, and maybe, if we lucky, it might even answer some of the unresolved unresolved and abandoned plots from GoT