Well so far I am still on the first book just before the Eddard dies and I enjoy GRRM's writing style. I cannot objectively say if it is good or bad since honestly I didn't read that many books in my life. At least not in this genre.
But the again, I started the books long after watching the series and so for me it's more like expansion of character's depth and the world. Which is good enough to me.
Also I really enjoy the chapters being centered around one character and the jumps between the chapters. I usually cannot read more than like 40-60 pages of any book at one time anyways so it's nice that I can just read three-four chapters whole and start on fresh chapter the next day. It fits my reading style perfectly.