Thanks for your question.
You're right that it's not a typical Java EE book as it covers only the new features in Java EE 8 while most other books cover the entire platform. I believe that developers who already know Java EE 5/6/7 or who are learning Java EE will benefit from a book that covers the features they don't know (i.e. the new bits), rather than pay out $40 for a book that contains mostly content they already know. They would have to filter through the book looking for just the new bits. That's time-consuming and most developers don't have time to read unnecessary content. So was born the idea of a book containing only new content.
So, if you are a Java EE 5/6/7 developer then every chapter contains information, code examples, technical explanations that you have never read before. You learn something new with every paragraph. That's the objective.
I had to read through all the specification and fish out the new bits, I had to figure out how the API works (or didn't work) and create code examples for each new feature (the book comes with a GitHub repository). It took a few months but I got there.
I am offering JavaRanchers a special price of only $9.95 (suggested price $19.95) direct from leanpub: Java EE 8: Only What's New JavaRanch special offer
. Or maybe you'll win a copy!!! Good luck.