Basically... eh.
I think what mostly bugged me was the style of writing - I know it was supposed to feel as if the main character is telling me the story, but that just means everything is described very flatly and told in a sloppy, slangy style. I think the story could have been much more interesting and touching if it was told well, but with this style I didn't really get attached to any of the characters, and wasn't able to try to imagine how they were feeling - because the text itself barely described that.
Also, again (as happened in the last book I read, by the same author), there was a relationship between a teenager and an adult, with no one thinking it's weird or bad (this time, a 19-year-old girl in a relationship with a guy who I'm not sure how old he is but is definitely an adult, and also a slave owner who was probably planning on buying her if she didn't love him back). It was frankly just gross, and everyone acted as if it was completely normal, even in a modern human world.
I did like the ending, because a lot of seperate things (not everything, mind you) suddenly got connected. Again, though, I think I didn't really feel anything for the characters themselves or what happened to them at the end (no spoilers), which is kind of sad because this idea could potentially really hurt me (in the nice and warm way that good books do) if it was more well-executed.
(I also liked the idea of Helen's hair, that covers her face and you can tell her mood by how much she's covered by it: all hair behind her ears, only one side behind one ear, only her nose popping out, or completely covered. Might steal that for one of my stories one day, idk, it's just a nice concept.)
To summarize - cute idea, poorly executed.