The book was very thought provoking at parts, and provides a lot of reasoning behind why we might receive a message from the stars. More than being about the motivations of alien civilizations, the book is about one of the central figures in the attempt to decipher the message, and the characteristics of his peers, and the organization that is charged with studying the phenomenon.
My main complaint with the book is that there are long sections (sometimes entire chapters) that are abstract and philosophically dense. I was unprepared for those sections and found myself reading straight through to get to the more plot-focused sections. I found the writing style (perhaps it is something lost in the translation) overly scientific and dry.