I really enjoyed this book! I figured out the secret before I'd hit page 50, but the story was so enjoyable I didn't mind going along for the ride anyway. Some of the characters were a bit thin (notably Adri and the stepsisters -- though they always were in the fairy tale, too), but Cinder and Kai were wonderful, and I especially loved Iko and Dr. Erland. I enjoyed the twist on the setting and the characters. The world building was solid, though there were things I had difficulty picturing early on (what Iko looked like, for instance).
There were elements that felt eerily familiar...but that's probably just my weird smattering of interests coming through. Like, the cyborg teenager that reminded me of Cameron in the Sarah Connor Chronicles, or the person who'd been in a terrible accident and got patched up with cybernetic protheses (or...augmentations?) without their knowledge/consent, like Adam Jensen in the Deus Ex: Human Revolution game. But that might be coincidental -- I don't know if Meyer had any familiarity with that game, and it was just released last year, so...probably just my mind making connections.
All said, this is the best book of the last several I've picked up, and I'm really looking forward to #2!