I'm a very active NetBeans Platform developer, so I've been aware of this book since the author published the original German version a couple of years ago. It's been highly acclaimed by German developers, but unfortunately, I don't read German well enough to understand an entire technical book written in the language. There are a few English books about the NetBeans Platform and I've read them all cover to cover (and in one case, was asked by one of the authors to perform a technical review of the manuscript). Now that this English translation is available I can say that The Definitive Guide to the NetBeans Platform is unquestionably the best book currently available about the NetBeans Platform.
I'll begin by stating that this review is based solely on my honest assessment of the book. The publisher offered me a free review copy of this book before publication, but I declined and instead purchased my own retail copy. And while I do know the author and many of the book's translators from the NetBeans community, they haven't see my review before I posted it here.
This book is appropriate for developers who have at least intermediate experience with the Java language but it does not require any previous experience with the NetBeans Platform.
It begins by explaining what the platform is and what needs it fulfills. While the prose is generally effective, the diagrams (particularly in the architecture section) do a great job of illustrating what different subsystems do and how they work together. The book continues by covering many of the major conceptual divisions of the platform (actions, user interface, file IO, data persistence, internationalization support) in detail.
The book concludes by putting these concepts into practice by walking the user through a complete example of a real-life application (an MP3 manager) which ties them together. Although this particular example might not have an apparent benefit to business application developers, it's easy to understand and demonstrates the same techniques you'd use to develop a typical business application.
There is also a chapter which explains how to migrate from the Eclipse RCP to the NetBeans Platform, but this would also be useful to read for anyone who is evaluating application development in either environment.
The book's strong points are its technical accuracy and the thoroughness in which it explains those topics it covers. I've been developing NetBeans Platform applications nearly every day for the several years and I still managed to learn some things from this book. Furthermore, this book has been updated from its original German version to cover the recent 6.5 release of the NetBeans Platform and it's the only book available that covers some of the newer APIs.
The book's main weak point is that it doesn't cover some topics (like testing, lazy loading and configuration management techniques) which are important to the overall development lifecycle of a production NetBeans Platform application. Although the translation effort was quite good overall, a few "Germanisms" still made it into the final text. I found them more amusing than annoying and they didn't interfere in any way with my ability to understand the book.
Giving this book five stars would imply that there is no possible way to improve it, so I've rated it with four stars although I'd give it another half star if the review system allowed.
In conclusion, I feel that The Definitive Guide to the NetBeans Platform is a worthwhile investment for any experienced Java developer who wants to learn more about the NetBeans Platform.