At heart, this book is about transforming the written word into money by selling products. In a larger sense, it's about how to write to convince, a technique that is useful to pretty much anyone. If you never write to convince, you might at least be interested in how other people are trying to convince you with their writing.
I'm not that great a writer, so advice in how to improve is useful, and the author does a good job of conveying some useful principles.
One thing that's weak in the book is that the author made his money in the 70ies and 80ies, and while the book has had a retrofit for the web, it's clearly not what it was written for or about. I think that most of the principles translate fairly well for the web, but not all of them, and it's worth reading it with a critical eye from that point of view.
This would be a great book to use for a course: I felt that reading straight through it without practising some of what's illustrated was probably less than ideal, so I hope to go back and reread bits and pieces and attempt to put them in practice with some of my blog posts / emails for LiberWriter.
I suspect that reading more on the subject wouldn't hurt at all. Any suggestions?