I enjoyed the progression of the characters. They stayed true to their nature, but their back story evolved more. While I thought some would turn out bad, they don't and some could be good and they're not. Gemma faces a new set of challenges this time. She and her friends have left the school for Christmas holiday, so the setting changes, which is nice. Basically, what I'm saying is... I enjoyed the first book and the characters haven't lost anything in continuing the story through the second book. (which happens so often in teen lit-fantasy)
I'm curious to see how Simon plays out in the final book. Will he stay or be replaced? Kartik, I know won't last... though he would be my choice.
Great book 2!