"We the Media: Grassroots Journalism by the People, for the People" is a solid, detailed and highly readable book. And it is an even better web site.
The major problem with the book isn't in the writing, or the facts, or the detailed research, the problem is that the people and organizations who need to read it most, the people involved in managing major print and broadcast media, won't read it.
Where author Dan Gillmor has a weakness is his basis that media is focused around news, gathering and reporting. This hasn't been the case for decades, media is about selling advertising, aggregating an audience, and putting in enough content to keep the ads from bumping into each other. Mostly teevee, radio and daily newspapers aren't in the news business, they are in the infotainment business.
While he does a great job showing how internet tools enhance and empower internet citizens, the examples he cites from major media are the exceptions. For the most part, with increasing consolidation, major media either ignores the internet or treats it as an electronic version of the way they have always done business. In most towns and cities in Canada and USA, print, radio and teevee have abdicated their role in the community.
This book is a great resource, and if you are an active participant in the internet, there are probably many passages where you will find yourself trying to click on the page for the relevant link, and then draw back because you realize it is just some marks on paper, it isn't information.
However, there is a web site, and the text of the book is freely available via a Creative Commons license. This is one of the best new media books of the year.