I'd always assumed that financial reports were best left to CPAs, that they were simply too complex to be understood by a layman. I found it not only useful, but I also really got into it and wanted to start looking at everyone's financials to see if I could help them improve their business with my new knowledge.
Anyway, I think this book is immensely useful for self-employed people and small business owners. You'll learn not only about the Balance Sheet, Income Statement, and Cash Flow statement, but also how they work together to give you both big-picture views of your financial data, but also insight on how the small details fit together to tell you where you can improve your business.
Really fascinating read, can't wait to pick it up again for a refresher.