I have a large number of metrics books, including everything written by Grady, Jones, and Florac & Carleton, and this is one of my personal favorites. It not only goes into measurement theory and practice, but covers nearly every key metric associated with software engineering.
Instead of writing a tome about what this book contains, I'll confine my comments to what I especially like about it and why.
First, the measurement fundamentals, the goal-based measurement framework, and information about data collection and management alone make this book worth owning. Data collection, for example, can waste resources if you try to collect everything, or worse, don't properly manage or analyze it. Follow the process given in the first part of this book and you'll have a solid basis for a metrics initiative.
Second, the scope of software engineering metrics is wide and given fairly detailed treatment. I especially like the fact that object-oriented metrics are addressed, and the multi-dimensional approach to measuring internal and external product attributes. Moreover, the scope of this book extends to productivity and resource management, which is where development projects and lifecycle costs associated with maintenance have gaps. Finally, the section on software reliability metrics was excellent and added yet another dimension to the coverage the authors give.
Overall, this book is both rigorous and practical as the title implies. The theory and practical applications of measurement and metrics are carefully balanced, and the breadth of material ensures that coverage is complete and addresses all major aspects of software engineering.