I'd rate the first half of the book 5 stars. The latter half of the book gets a bit muddled as some plot lines take longer to explain than they do to resolve (what if aliens could hide by only moving when the eye moves? nothing very helpful for them that's what), and an extended tirade on the uselessness of self-awareness for survival which i think i disagree with - philosophical reasoning aside, a dog knowing that it is a dog would seem very useful in a wide variety of survival situations.