From the reviews:
The book provides a comprehensive and up-to-date treatment of generalizability theory. It provides a synthesis of those parts of the statistical literature that are directly applicable to generalizability theory. Mathematical Reviews
...This book belongs in every measurement specialist's reference collection, as a resource to which to turn for insight into virtually any question about GT, whether it deals with univariate or multivariate applications. There is simply nowhere else to get such a comprehensive presentation of the theory. Psychometrika
This book fills a need for up-to-date presentation, critical review, and analysis of issues in generalizability theory, particularly in multivariate generalizability theory. Brennan has for many years been at the forefront of research and development in generalizability theory and he provides a well-written, thoughtful, focused analysis of recent issues. I would highly recommend this book to anyone seriously interested in learning about generalizability theory. It is an excellent resource for anyone wanting to use generalizability theory in research ... . (Laura L. B. Barnes, Journal of Education Measurement, 2002)