Marissa Meyer writes fairy tales in a dystopian future of high technology and little hope. Cinder, the protagonist, is a homologue of Cinderella. We have a Prince, an evil stepmother, and other aspects of the famous tale, but the original story is used as a device to articulate a much larger narrative, a story of terrifying danger, not only for the protagonist but all of humanity.
I really like what the author has done, especially the technical aspects that are at once ultramodern and, yet, full of the same quirks as our world that keep the maintenance people in business--a good thing since our protagonist is a mechanic.
The world-building is intriguing, but what I most enjoyed was the sarcastic wit of the protagonist. All of this helps build a likable character, and it works very well. It's even more than the story. The book challenges assumptions about race and a woman's role in a fantasy setting. Our protagonist is a heroic figure who uses her brain to vanquish disaster. It's easy to cheer for Cinder.