First, history is very rich, told from the perspective of a different character in each chapter. The main plot is full of small subplots, psychology of the characters is very detailed, and it is especially on this point that the work stands out from the traditional to the JRR Tolkien fantasy. Here the heroes also have shadows and the bastards are not so vile we could conceive at first. No battle of good against evil, simply destinies, the great lords and bastards, brilliant and intriguing too proud people to compromise their honor, but all have their part to play in a world where everyone, hero and bastards young and old, can fall, apart from the board or killed.
The story is excellent, the language is rich, the story full of surprises. GRR Martin made there more than writing an excellent series of fantasy, it defined a new standard whose scope is not limited to one genre.
A series put all hands (adolescent-adult audience however), provided that players / readers are not décoouragé-es by the length of stories (1000 average pages per volume).