Yes, there are elements of other books/movies in this but it's all done so originally I just didn't care. The biggest problem(??) is that this has just enough romance and "chick stuff" in it to keep my boys uninterested (this happens with Meyer's on-going vampire series as well). But Melanie/Wanda is such a great character, and let's not forget the interesting question raised: what is "human", exactly?
I hope this is not part of a series, but my guess is that it will be (an unfortunate pattern with bestselling YA books these days; original one-off is out, series is in).