The thing that always factors into adaptation is the fine line one has to walk between, retaining a faithful direction to that of the source material, while also being able to create amazing drama and interprate the story in such a way that it feels new and fresh to all audiences. It can at best be summarized by quoting Joseph Conrad "'My task which I am trying to achieve is, by the powers of the written word, to make you hear, to make you feel-it is, before all, to make to see'.
Or otherwise, by D. W. Griffith whose cinematic intention at his time were recorded as such: 'The task I am trying to achieve is above all to make you see. George Bluestone's all-but-pioneering work in the film-literature field, Novels into Film, which in of itself claims that 'between the percept of the visual image and the concept of the mental image lies the root difference between the two media'. In most cases, and in this one, books & film. He acknowledges the connecting link of 'seeing' in his use of the word 'image'. At the same time, he points to the fundamental difference between the way images are produced in the two media and how they are received. Finally, though, he claims that 'conceptual images evoked by verbal stimuli can scarcely be distinguished in the end from those evoked by non-verbal stimuli, and, in this respect, he shares common.
It's even crazier with something like A Song of Ice & Fire, where you have a fantasy story that hasn't even been written yet.. at least not to the end; Understanding that, the showrunners have more or less taken a gamble, because they know what they want to do with a Game of Thrones. They want to create good drama, just like Ole Bornedahl wanted to do with his 1864 series, like Spielberg wanted to do with Band of Brothers & The Pacific etc. I do, however, think that Game of Thrones (the show) has deviated itself too much from the books in such a way that I can hardly recognize it some time, but I also recognize that it's still pretty entertaining to watch. Telltale's game is pretty fun! Because I still like how the core intrigue of the books have been kept there, but I always remind myself how irritating it is that said game had to tie itself down to the whims of the show over the books -- Because it usually derives it down to one big piece of merchandise or marketing board at the expense of the tv-show. Looks here's Peter Dinklage! Here's Lena Headey! etc. Lately, it's gotten better at least, recent episode has had least guest cameos and a stronger focus on The Forresters. But ultimately it still carries the legacy of a tv-show and it's always such an annoyance when a tv-show has to be tied to a game (looking at you Remedy).
Anyway, as adaptation goes, I think Game of Thrones does it alright, but I couldn't help but lose a lot of interest by the end of the 4th season. There was just something about it's rather jarring handlement of the Hound's end of which Brienne of Tarth would arbitrarily show up and kill him, then Arya would run away. Blergh.