This book was totally compelling - my copy is now completely covered in crib notes - having devoured it at some speed I now want to go back and read the whole thing again. Not just interesting for people working in marketing, but also for those, like myself, working in small businesses, or, frankly, anyone interested in social psychology. Put simply (although there's nothing much simple about this book) Mark investigates how we are less driven by independent thought than we would like to believe, and more by peer influence; more than simply recapitulating that word-of-mouth is the best form of marketing (something we already knew) he gets right down to the roots of how it occurs, who perpetuates it and what it actually consists of, throwing up some fascinating insights into human behaviour in the process. He then strips back many existing marketing assumptions and presents some compelling new ideas as to how these theories should affect marketing in the modern world. Marketing tips aside, the book leads you to re-examine your choices, decisions, preferences, taste and even identity. It's immaculately researched and a totally absorbing read. Steven Poole in the Guardian compares him to Malcolm Gladwell on speed; I'm thinking more Robert M Pirsig with a point.