The book tells the readers how "word of mouth" works to create buzz, thus promoting the products.
The start of the book is interesting and it gets more boring towards the end. Although quite a number of examples are cited, they are quite repetitive (and outdated as it was written in some years ago, e.g. it only cited Hotmail but not Google as an example). Somehow it cannot jump out the trend that it's just a book which uses hundreds of pages to elaborate a small idea, i.e. a reader can jump a few chapters without losing anything valuable. And most of the contents in the latter part are just old wine in a new bottle.
Anyway, the idea in the book is quite inspiring. It worths spending some time.
If you don't know whether you will be interested in it, you can go to the author's website to take a glance first: