Maguire gives some simple, practicle advice for improving the development environment that a manager is responsible for. For example, he recommends starting each day by asking, "What can I do today that will help keep the project on track for the next few months?"
I also found the section on feedback loops to be interesting. The suggestion that you have a person stop feature work to fix a bug that they created as soon as it is found is a way to emphasize quality and make it in the best interest of developers to produce high quality code.
The chapter on attitudes is also very good. Much of the time, there isn't a lot knowledge wise that separtes good and bad developers. The difference comes in attitude. Attitudes such as, "We can't do that!", "The users won't care!", "Bugs are going to happen!" need to be rooted out.
This book gives good insight as to what you as a manager can do and help your developers do in order to have smoother projects that are high quality and on time.