Fr. Mitch's book is an introduction on how to deal with these frustrations. It isn't a book that will help you to quiet your conscience if it is flaring up. It isn't there to guide you into a "you are okay, I'm okay" analysis of your inner-child. What it does is helps those that have genuine frustrations who are within the Church. There are no quick-fixes or easy answers. That may turn some off, because they actually might have to study or work at changing themselves (the place where the frustrations lie).
Practical and hard advice peppers the book. It is a quick read and easy to read. If frustrated, you might give it a try.