I'm not sure what to say about this book, so I'll divide it into two chunks: 
 The Good: It's well-written and moves quickly. There's no moment when the reader feels bogged down. Transitioning between a past story and a present story is difficult and although the first time it happened was a little jolting, I adapted to it fast. In many ways, both stories -- about the modern girl and her troubles and the "wyrder" and her sister -- are equally engaging. The dialogue is never stiff and it doesn't have too much description (but enough). 
 The Bad: It's not very deep and a lot of the initial responses to members of the opposite sex are simply lust. Lilian wants Cade the first time she sees him, and that never subsides. We find out later the reason why she's such a sex-charged character but even that doesn't really compute, since lust drives ALL the characters. At one point, the king of the faes transports the wyrder into fae country... to seduce her. Why? She references her plainness several times, so why would this fae king want her so desperately? Fortunately, the sexual aspect is never all that graphic (talk of burning loins and such) but still, it's uncomfortable and makes the story more torrid than it needs to be. 
 Overall, I'll read it again -- but for such a good writer, it needed more than sexually charged emotions behind it.