Truthfully, this book covers SketchUp topics that no one's even come close to explaining in previous volumes: terrain modeling with the Sandbox tools, techniques for working with huge models, how to wrestle CAD files and using Ruby scripts, just to name a few. He also writes about something he's dubbed "SketchUp Process Modeling", a start-to-finish workflow for completing massive projects without losing your marbles.
The book includes hundreds of beautiful color images with helpful annotations and captions. Flipping through it the first time, I couldn't believe how much work Dan must've put in. He's a practicing landscape architect who uses SketchUp every day in his work, so the material's relevant to pros in a way that most books aren't.
Be sure to take a look at the website Dan built for the book, and be sure to check out his YouTube videos; they're great.