I've never been that excited about A Song of Ice and Fire. I think George R. R. Martin is a terrific writer, but this series leans far too heavily toward the political for my taste. As with Katherine Kurtz' later Deryni books, it sometimes loses track of the fact that politics and pageantry are decorations for the story, not the story itself. Song stays just on the right side of that line by offering lots and lots of interesting characters, and telling us enough about them as people to keep us going. It also enthusiastically embraces reality by killing and hurting people as needed for the story, rather than going for the usual happy fantasy ending.
I find that Song doesn't make the most of what Martin does best, which is to deal with human relationships. They're in here, and they're generally well-handled, but there are simply too many of them. The books are too large and too complex to really get a handle on, and the location and point-of-view changes too frequent to really get caught up.
I like to re-read prequels before launching into the latest book in a series. Here, I didn't have that option, and I probably also just don't have time to re-read the previous 4,000 pages. Since it had been almost 8 years since I read Storm, I didn't remember details that well. That problem was compounded by having seen parts of the HBO series, which in part helped me remember, in part confused my memory by changing or omitting elements.
The result was that it took me almost half the book before I felt I'd found my footing and remembered the essential details about most of the characters. A lot of the color, however, and much of the genealogy didn't come back, and I didn't have the patience to read through the hundred pages of family trees in the appendix.
All that said, this book carries the story forward, continues to deal largely with interesting, human characters, and jumps nimbly from setting to setting. I had some qualms about how both Jon Snow and Daenerys were handled, with some of it seeming a bit out of character, but most was well done. That same setting jumping, though, stood in the way of Martin's writing strengths. The chapters are too short to make much progress in character development before they're interrupted by the needs of another character somewhere else. When we at last come back to the first viewpoint, it takes time to re-establish our empathy and interest.
Finally, the editing is good, but imperfect. What is it with talented writers and vocabulary these days? Martin makes the same misuse of 'whence' as Robin Hobb recently did (to indicate a destination, rather than an origin), and he misuses 'anon' from time to time. Both are experienced fantasy writers, so I don't quite know what to make of it. Carelessness, perhaps.
All in all, a solid continuation of the Song of Ice and Fire series, and a must for its fans. I hope it's obvious that newcomers should not start here. If you like dense, well-written political fantasy, this is the series for you. If you're looking for a fun quest with magic swords and dragons, look elsewhere (though the book has both of those items as well).