My wife bought this for me on a whim for my birthday, and I am so pleased! As far as I know, "Sophie's World", by Jostein Gaarder, was the first book that explicitly directed philosophical questions at people from smart teenagers upwards. This is the second. A variety of philosophical questions (Is death the worst thing that can happen to you? What is happiness? Do we have free will?) are introduced to a teenager, with characters around him arguing from different perspectives. As tends to be the way, no conclusions are really reached - but by the end of the book, Ben has (and hopefully the reader will have) a more thoughtful perspective on the nature of life, the universe and everything.
The principal characters (Ben and Lila - to what extent, I wonder, is the author writing herself into the part of Lila?) are sympathetic and well-painted. The plot is imaginative and playful. The writing is snappy and clever - "Ben had heard of Plato. And now he'd seen his sports car, he was even more impressed." And if we are really homo sapiens, then we ought to be thinking about the issues that the author discusses.
Please write some more, Ms Eyre!