If you are reading this book and expect to understand the second day after how opensource works, you are plain wrong. You should actually stop reading.
But what this book does, it does with style.
It presents you how opensource projects manage to create the best of the breed software, how you can track changes in those projects and understand why some software got the way it is, how can you alter it to fit your needs. It actually gives you valuable insight upon code analysis, and how to get a grip when you have a real big code in front of you and don't know even where to start.
If you will understand that this books explain you a process of creating software (which in no case happends over night) you will love this book... otherwise this will be just another technical book, explaining sometimes apparent obvious stuff.
Because this book has great insights from the years of experience of the author, I can not give it less then 5 stars and suggest it as a required reading for anyone who considers entering the opensource developer's world.