I gave this book four stars because the storyline was very interesting and engaging. However, I must say that this book is in desperate need of proofreading and correction. Above and beyond the numerous puntuation mistakes, there are several instances where there are small problems with continuity. For example, in the scene where Chloe and Seth break up (in which she is standing and he is seated across the room from her), she begins by "Looking down at his hurt expression...", but after much dialog, we have Seth in the position of "...tightening his grip on her shoulders...". When did he stand and move over to her? It isn't written in the book, so how can the reader know?
My biggest complaint though, is with the massive overuse of the "uhhh..." I could almost excuse its overuse by Chloe, who we know is shy, a bit backwards, and has trouble using her words; but I cannot excuse the same "uhhh..." being used by Sam, Seth, Prof Willard, and Seth's mom. It is very off putting, and to be honest, if I had not been so interested in the story, I would not have kept reading after the 5th or 6th "Uhhh...", it is just that irritating.
Lastly, I have to say, the addition of the religion storyline near the end of the book, felt a little strange and forced. From Chloe's conversation with Prof Willard, to the whole scenario with the priest, it was just very abrupt and lacking in subtlety. I am not certain exactly what the author was trying to convey, but if the idea was to add a feel of science vs religion, it really could've used a bit more finesse.
I realize that it might seem bizarre to have this many complaints about a book that I've rated pretty highly, but realistically, all of the problems I have with it could be corrected through simple proofing/editing. The storyline itself is sound, and very, very good, and I am definitely looking forward to the next installment.