This book is a condensed series of thoughts on a subject that the author knows more about than probably anyone else on earth. Glenn Reynold's Instapundit is one of the few enduring blogs from the early days. The short-hand blog post comments he provides to linked stories are evidence of a seriously smart, thoughtful and funny person.
There are so many thought-provoking points in this short book; they just come one after the other. Most authors would not make so many cogent observations in a lifetime of writing. A must-read for anyone serious about knowing the issues surrounding social media.