This is the best book on the subject I've come across. It certainly lives up to the billing given by James Kasting, of Penn State Astrobiology Center, on the cover: "A lucid and surprisingly accurate introduction to the field of astrobiology and a thoughtful response to the Rare Earth hypothesis." Chapter 6 pretty well demolishes Rare Earth and exposes its surprising creationist roots. Elsewhere, Darling explains when and where we might expect to find extraterrestrial life, what methods we'll use to detect it, the missions and projects planned over the next 10-20 years, the latest on the controversies surrounding Mars, the Martian meteorites, Europa, organic matter in space, and extrasolar planets, and the principles that might govern life wherever it appears. He manages to cram a huge amount of information and ideas into a small space and yet it's so well explained you never get lost in the detail. It's hard to believe that the "reader" who gave the book only two stars actually read it at all. I can see how it might not be popular with those who want to cling to the belief that the Earth and humans are somehow special. But the fact is this is first-class science in a first-class package.