Berger's work takes up where Malcolm Gladwell's The Tipping Point leaves off.
Gladwell's book is an overview of how ideas and social behavior go viral, while Berger's work takes an in-depth look at the common characteristics of things that become contagious. Gladwell's and Berger's books compliment each other, and provide helpful tips for getting a product or idea to spread.
Contagious outlines six principals that prompt people to share content, opinions and ideas. They can be one or more phenomenon including include social currency, triggers, emotion, and practical value. I was impressed with how easily Berger was able to explain his theory.
I listened to Contagious as an audiobook. I enjoyed the narration by Keith Nobbs who has a long list of audio credits to his name http://www.recordedbooks.com/index.cfm?fuseaction=rb.show_narr&narr_id=4533
I awarded Contagious by Jonah Berger four stars on my Goodreads Page