The difference between a book and a blog is that a book has a narrative or an argument; whereas a blog is a series of thoughts, not necessarily connected.
And narrative is what's lacking in this book. Like Seth's other works, it seems to have been taken from blogs written over time. Many of the headings cover similar ground, so the book becomes repetitive.
And because there's no argument, the central idea of the book never really develops. Seth just keeps looking at the subject from different angles.
This is frustrating, and it's a shame, because Seth Godin is an original thinker and this book is a good example of the clarity with which he can see 21st issues, especially as they relate to the online world.
Seth also shies away from making any practical suggestions about how to create a Tribe.
However, the book is good on Leadership. If you're interested in that subject, it's not a bad read.