The Marquess is a conniving, cunning creature and she makes a wonderful foil to September. I enjoyed how September realized that she had in fact started to grow a heart that she would consider that her mother would miss er if she were to stay in Fairyland forever. I like that the Marquess has been put away for use later as well.
There are places where the book distinctly echoes The Oz and Narnia series, particularly with how children cross over into Fairyland and how time functions for the Ravished and the Stumbled while there. I like that September takes Dorothy's tack of "I have to go back to my family" instead of how the kids in the Lion, the Witch and the Wardrobe are there more to not deal with the gravity of their real world circumstances, although they adapt to returning in a vastly different way than the Marquess does and for good reason given the Marquess's home life.
What are everyone else's thoughts?