I'm sorry to hear that you're disappointed with the book.
From our experience, we've found that the best way to learn a new concept is to really focus on the core concepts and ensure that those concepts are well developed and presented. We've found that once the reader has completely mastered the core concepts, more advanced concepts become rather easy and often require little explanation.
We try to stay away from complex examples that only briefly mention the core concepts. We've all experienced the scenario where we've been trying to learn a new topic, and once we "get it" or "the light bulb comes on" the topic seems much easier. We've found that the fastest way to "get it" is to completely master the core concepts first.
What suggestions do you have for making the book better? Since the Java landscape is so big we wanted to expose readers to the most popular Ajax concepts and how they relate to the most popular frameworks.