This book seems to be a pretty comprehensive "jumpstart" into IPv6. It covers the rationale for IPv6, before diving into a fairly thorough walk-through of configuring systems for IPv6, from host addressing and routing and on to applications. There are also good chapter on IPv6 internals, for those interested, and security.
The book is mostly practical, focused on the operational issues of IPv6 primarily, providing both the background of understanding and, usually, configuration examples of the (many) technologies discussed. The book is also sprinkled with interesting digressions, helpfully boxed off to avoid distracting from the main content. For those already familiar with IPv6, the book won't be too interesting. Even so it covers so many technologies and platforms (e.g. 6to4 configuration for various platforms) there may still be useful or interesting information, particularly in the background provided.
For those needing to get to speed quickly on IPv6, this book may give a comprehensive, yet concise, insight into real-world IPv6 operation.