For a concept that has so much a place in b-school discussions, you might think the book focuses on the 5-forces, but it is only a small part of the book. It outlines the Generic Competitive Strategies (again, a now well known topic), Competitor Analysis (extremely valuable), Market Signals, Competitive Moves, and so much more.
The book is in three parts, General Analytical Techniques, Generic Industry Environments, and Strategic Decisions. There is an appendix on Portfolio Techniques in Competitor Analysis, and a very useful appendix on How to Conduct an Industry Analysis.
I think a lot of times this book is not given as active a place in the pantheon as it deserves because so many books and articles are recycling a lot of what was in this book and most don't add much to the discussion. Honestly, this book is worth referring to over and over and over again. It is a tool or a weapon in your competitive war chest that needs to be kept active and in play.
And only after reading it, are you fit to read the sequel, Competitive Advantage, which if you haven't read till now, makes you unfit to talk about business tactics.
These two books are the Old and New Testaments of business.A must have for beginners A must have. Porter provides students with a great place to start for understanding strategy. While you must know the basics in this book to understand the foundation of strategy,it will not provide you with a dynamic and cutting edge strategic framework that many of today's industries need.