Kristin Cashore is an extremely talented writer. I very much enjoyed Graceling and Fire. And the feel of Bitterblue is beautiful, from the book design, down to the prose, but I think that perhaps Cashore tried to put too much into this book. 
 Sometimes if we have a lot to say, if we say it all at once, it can come out jumbled. This book was full enough of ciphers and mysteries and convolutions that it didn't have to throw in things like (view spoiler)[a hint that Bitterblue's love interest is bisexual and Bitterblue not batting an eye at this, because, of course, she's okay with that. At any rate, there were a lot of issue-y things like this that snuck in - which is fine as long as the story doesn't lose its story feel and become more like a platform. It's almost as though Ms. Cashore felt that she had to include all of her stances on issue-y things in this book. I don't have a problem with any of her views, I just felt that sometimes they seemed to be pushed into the story. Perhaps she could have included less issue-y things here and spread them out over future novels so that her stance would be clear, yet not thrown at us all at once. (hide spoiler)] 
 Although Bitterblue is a beautifully written book, it seems that it could have said less in a more straightforward way and still have had the same impact. Bitterbluemay leave the reader feeling a little frustrated that the story wasn't smoother, and they may come away feeling as though they have read beautifully written words, and yet realize that they are unsatisfied in an unfilled sort of way.