I thoroughly enjoyed this book. There were a few problems - mainly, that it was predictable. But any author who can take a fairytale and turn it into this is pretty talented.
I enjoyed the characters - none of them are really formulaic, as such. I would like to have known more about what was going on in Kai's head, but then again - Cinder was the main character. Some things seemed a little too-good-to-be-true, like this friendship between Cinder and Kai. But hey, it's Cinderella we're talking here, so all the rules are put on hold.
This isn't the best book I've ever read. But it certainly was enjoyable.