I can see both sides of the books vs show argument...
Early on, the show really did an incredible job of adapting the books. Season 1 is basically Book 1 scene for scene. Sure some detail got cut, but if you go back its astounding how many whole chapters make it in, in sequence. Season 2 is also very close. I think the first big departure is Robb's wife, and after that it slowly begins to fork into its own mythos. I find I was enjoying the show less, due to the differences, in seasons 4 and 5. Now that the show is in new territory, I think I'm being a lot more forgiving and I enjoyed S6 the most since very early on.
The show has ended up being very different though, compared to how accurate it was in the beginning.