Overall I enjoyed this book, even though it didn't quite seem to find its footing as either hard science fiction or a sweet romance. The lead character, Rachel, was a bit annoying as she seemed a little too naive and willing to become an alien collaborator with no second thoughts and too blase about the entire thing (that willing suspension of disbelief). On the other hand, once that premise was accepted, viewing an alien invasion through the eyes of somebody who supported them was rather interesting and quite different from the usual kick-butt heroines you see in science fiction today.
I did enjoy Peter very much, though, and the world that was built with the alien spaceship and the reason the Ancients were rolling out a plan of assimilation. When Peter ran into trouble with the resistance, the story got page-turningly interesting and I ended up staying up late at night to finish the book.