This is the first book available that describes the functionality of the Pentaho Report Designer in detail. Will Gorman mainly focused on integrating the reports in Java applications and not so much on using it in combination with the Pentaho BI Server.
Overall, it is an excellent book. It guides you through various tutorials on how to create more complex reports. All the tutorials are fairly easy to follow. Some chapters of the book give a very detailled description of the available functionality and settings, which serves as an excellent reference.
Conclusion: I really enjoyed reading this book. From my point of view Will Gorman provides an interesting overview of Pentaho Reporting. If you are one of those users that are not familiar with Java and just want to get a general overview of Pentaho Reporting, then this book will also be a good ressource as well (just skip some of the pages then that describe the Java integration).
I hope that there will be a Part II of this book, as I certainly would have liked to know more about adding OLAP and Metadata sources to the report and parameterizing them.