Definitely the best of the series so far, this thing is absolutely massive (and I mean that in terms of both size and scope). It hurt my brain to read it, and it hurt my hand to hold it.
Where A Clash of Kings felt like it was setting things in place, Storm of Swords got things moving, and it got them moving fast. Plot, character development, world building, and foreshadowing, all of it starts moving at lightning speed in this book, and it doesn't let up until the very last word. This is the book that put this series on my favorites shelf, because this was the book that made it clear that Martin isn't just out to write gritty fantasy that breaks all the rules. He's writing a damn good story.
It is one of my favorite things in the world (and something I'll elaborate more on in my review of A Feast For Crows in a couple of weeks) to experience a truly good character arc, one in which a character transforms naturally from one thing to another, and actually changes in real and believable ways, and for real and believable reasons. Martin is a master at this, and it's only book three. I can't wait to see where he'll take all these people by the end of book seven (those that don't end up dead, that is). It's going to be delicious.
[First read, July 2007]