I have read books first, then seen films, seen films, then read the books. To me, it doesn't matter. I just contrast and compare the two, because I know damned well that there will be inevitable inconsisntencies between the two.

Sometimes for me, it's easier to visualize what is happening in text when I have clear understanding of characters. Of faces and mannerisms, and voices/accents.

If this were the Wheel of Time, I would say you'd have to read the books first. Too much crazy detail to miss in my opinion.

I haven't yet seen the series, so I don't know how much of the storyline or character development they are trimming off to cram one book into a season. Depending on that, you might want to read the books first?

Neither my mom and my sister have read them and are watching the series (I refuse to pay for cable or dish). They both say they have no problem following the storyline, and they haven't asked me questions like, "but why is Ned talking to this person about x ..?"

I've seem some movies before I read books, and was like... "but who is that? and why are they pissed off at each other?" I don't think you'll have to worry about that in this case.