Not only does Meyer introduce her version of the Rapunzel story in Cress (complete with unlikely prince character), but she keeps her Cinderella and Red Riding Hood narratives going. It looks like the next book, Winter (forthcoming) is going to introduce her version of Snow White.
In order to keep all the threads active, the books are becoming quite large. This one was over 500 pages, but very engaging and easy to read, and it was great to see Kai and Cinder get some more page time in this go-around.
This is sci-fi/fantasy soapy drama at its best complete with weird medical experiments, sentient androids, and mind control, but all in a good way. Alliances are tested, preconceptions are questioned, and the characters continue to be well drawn and funny, as well as empathetic. The best scenes are when the growing band of heroes are all together in a room/spaceship arguing with each other. The banter between them is priceless. I could really see this series as a movie - although I guess it would have to be a big epic series of movies.
Even though the books are large and there's a LOT going on now, I'm not going to be able to resist reading them as long as Meyer keeps writing them.