I work at a company that's been running a version of SAP that's slightly later than this book references, but we're now going to the latest and greatest version. I wanted to take the opportunity to learn more about SAP and how it works. This isn't a step by step instructions on how to operate SAP, but gives an overview of why you might want to.
I'm not completely through the book, but I'm impressed with what I've seen. The first part covers why companies would go with a ready made system like SAP and how they can use the expertise and templates that SAP has developed to restructure their business. It sometimes feels like such common sense you'd think of the things, but it's good to actually read it and see it structured. This would be an exceptionally good section for companies trying to decide whether to go with a custom built piece of software or to go with something that's ready made and try to adapt themselves to it and it to them.
Later parts of the book get into more real and hypothetical scenarios on how you'd analyze and lay out set processes. For example, you'd go through how an order system would go from planning stages to taking the order, to manufacturing, and then shipping it and billing the customer. It's a good mental exercise in bringing together and helps you to learn to view the whole picture. You'll fast learn you should include people from multiple different roles/groups into one gigantic blitz instead of trying to manage things on a functional basis.
If your considering moving to SAP or just want a book to learn more about SAP, you have a lot worse places to start than this. Don't get too hung up with SAP versions, there are differences, but they don't tend to be drastically different. Even if you're not on version 4.5, there's still a whole lot of value in this book.