Most of the books in the field of machining are written in the style of textbooks, long on tables and charts and short on inspiration. Joe Martin's approach to the subject is to use plenty of personal examples from the real world of machining and heavily illustrate the subject with color photos and line art. This book is equally at home on the coffee table in the living room or on the workbench in the shop.
If you have just bought a Sherline lathe or mill and are new to machining, this is an adequate resource and it does have scads of pretty pictures. You will quickly need more than this book.
If a friend gives you his old Sherline vertical milling machine, and you have no idea where to start, this is the book for you. Not only does it provide real guidance for getting started with small mills and lathes, but it manages to give you the basics without dumbing it down too much. The only problem, it was written so long ago that it lists rec.arts.metalcraft as one of the best online resources for people getting into the craft ((c)1998, after all). Other than that sort of update, the only thing I'd add would be more 'practice' projects.
Really amazing was that Chapter 3 includes a complete exploded view, with part numbers, of the Sherline lathe, Sherline mill, and Sherline rotary table.