At the *intersection* of software and business, and the business of software. The authors draw on research in economics, IT, and strategy and bring them together to draw excellent insights at their intersection. The book is not really about business or software per se.
Depending on your background, you might want to skip entire sections that are right up your own alley. If you are a manager looking to REALLY understand how the architecture of IT systems (e.g., at the enterprise level) interacts with business strategy, this book will provide a good exposure. If you are a propellerhead or uber-geek wanting to understand more about how your work shapes, hinders, or facilitates business strategy, this book is just right. I keep up with new research developments in the business of software and feel comfortable saying that the insights in this book are not to be found in other books that exist on the market.
The book is very well written, but be forewarned, it is deep. Fully appreciating it requires thought, reflection on what the authors are saying, and a tempered pace. It is not a quick read and not a "how-to" book. My only quibble with this book has nothing to do with its content: Once you get rid of the dust jacket, the quality of its binding and cover printing is absolutely shoddy. Very highly recommended and worth every penny of the forty dollar price.
Three year (June 2008) update on my 2005 review: Nothing yet comes close to the wide array of thought provoking questions that this book raises. I'm wildly speculating here, but the fact that one of the coauthors is an electrical engineer rather than a software developer is perhaps the reason why the nature of this book is so refreshing and original. Sometimes, it takes an outsider without the baggage of insider assumptions to bring a fresh perspective. At the new paperback price, it's better than a red-tagged bargain that you'd find at the aisle end caps of Target!