I don't know why there are not more reviews on this book. I read this book when I first started my 12-year career in the database industry. And to tell you the truth, there is only one other book I have ever needed (regarding database design) -- "The Data Warehouse Toolkit" (Kimball) -- only because Data Warehouse design is much different than the design theories in this book.
This book teaches you ways to design any database, and model any business -- what questions to ask users, what an entity really is, how you define it, how to tell a difference between an entity and an attribute, how to model relationships between entities, how to model "types" in a database. If you an learn the principles in this book, you will quickly become an expert in database design.
Buy this book -- you will not need another. And if you are building a data warehouse, buy this book first, so you understand the difference between OLTP design and data warehouse design.