I have found this book useful because of the level of detail and remarkable objective view about the aspects of methodology that works, that is to say, people-orientation.
Have you ever heard about that in order to be useful a methodology should be ‘instanciated’? In other words: an effective methodology is one that is adapted to a particular context . Alistair’s previous publications about methodology space convey the depth of what methodology entails , and what is to be considered for such methodology customization; somewhat recently, his publications focus on particular customizations becoming a ‘methods family’ called Crystal.
So yes, it has been very useful because has helped me to grasp in more detail what effective and practical methodology for small teams is all about.
 Just-In-Time Methodology Construction
 The Methodology Space