I don't read much fantasy anymore, most SF, but I've heard that aSoIaF is possibly one of the greatest Fantasy series of all time, rivalling even the great LoTR. I definitely want to read it, but he's not finished writing it yet and seems to be very slow, and I hate waiting for more books! Bah, I shoul probably just read it anyways.
I've read all of them except for the newest which I'm still chugging through and they are pretty hefty to get through. I absolutely loved them the first time I read them. There are a metric crap tonne of active characters in the books (far more then LOTR) and there are a lot of twists and turns.
Unfortunately with so much going on in the story I find that the large gaps between bookss can give room for you to forget exactly what is going on....though with the complexity and length of each book it's not surprising to see that it takes him a long time to put out a new one.
I'd still recommend that you start reading them now though as they are great stories.