I have been developing CakePHP projects for more than 4 years now and I really love this framework. There are people who has some opinions about how other PHP frameworks are better than CakePHP. But the reason why I prefere CakePHP is the community, the company - CakeDC and the support for old versions.
The main reason I prefer CakePHP is the speed at which I can create things. I have built smaller as well as very complex and vast applications. And for the performance, there are always ways to enhance the speed.
Croogo is a CMS built on the top of CakePHP which is an excellent example of what type of applications can be developed with CakePHP. CakePHP is just a framework - collection of things. Croogo is a CMS, where most common things that most of the web applications need, are built in it.
This book is mainly written for programmers who have some sort of experience in CakePHP, or at least an PHP MVC framework.