This is the first book that deals CTools. A great responsibility! Do not worry, it's a great book, highly recommended!
Will guide you in order to obtaining the basic knowledge of CTools & environment.
The focus is definitely CDF/CDE, with the guide of this book, you can create and maintain interactive Dashboards with multiple components.
Personally, I liked the chapter "Pentaho App Builder" in which explains how to create a new plugin through Sparkl.
My final appreciation: highly recommended!