It's hard to review this book because it was so meh. I wouldn't really call it a Cinderella retelling because other than the ball that everyone wants to go to and the wicked stepmother (who isn't a stepmother at all), nothing screams Cinderella to me. 
 The characters are either dull (Cinder, Prince Kai), annoying (Iko), or laughably cartoony (Queen Levana, Adri). The foreshadowing was so obvious it was like being hit with a two-by-four. Protip, constantly mentioning something every chapter, (in this case, the fact that the Lunar Princess is dead and if only she were still alive. HINT HINT HINT!) is not foreshadowing, it's beating people over the head with it and that only makes sense if your main character realizes the connection within a reasonable amount of time and doesn't have it spelled out for her at the end of the book. 
 Cinder as a character confuses me. Is she more human or robot? If the overlay in her system wasn't there, I would say human (since she just has a prosthetic arm and leg), but the computer overlay that lets her pull up information, sends messages to her body when she gets upset or whatever, and prevents her from blushing (wow, way to subvert the constant blushing heroine trope) makes her more machine to me than human, and I can't connect with that. It's like trying to make a connection with my microwave. 
 There are so many unanswered questions. Why are cyborgs considered second class citizens? Who are the Lunar? Why is Adri such a raging bitch? Why don't the Lunar overthrow Queen Levana if she's such a dictator? Instead of some history of the world, we get Cinder meandering around and making stupid decisions. 
 I probably won't read the next one.