Strong 4.5 out of 5. There were some parts that dragged a little, and the story was less about plot than about relationships (Katsa and Po, Katsa and her uncle) and showing a strong female lead character.
Parts I really liked: Katsa crossing the mountains with Bitterblue; Katsa showing up some tough guys who think they can pick on a girl. The are-they-or-aren't-they relationship between Raffin and Bann. (Others have commented negatively, saying Cashore shouldn't push the "homosexual lifestyle" on impressionable teens; I say that a lot of teens reading these books are figuring out their own sexualities, and need an example of a good, stable relationship. I also say that Cashore never says these two are gay, or in a romantic or sexual relationship, so maybe you all are projecting a little bit?)
Cashore does a beautiful job of describing the seven kingdoms, the scenery, the elements, the mountains and the ocean. I also enjoyed the dialog between Katsa and Po, and really her ability to write sarcastic, playful, humorous dialog.
I read this as part of the project to read Karen's list. I think she would have really enjoyed the book, although she would have been unhappy with the fact that Katsa and Po decide to become lovers without getting married. I definitely plan on reading more of this series when we're done with our project.