I was very put off by this book initially for reasons that I see in some of the other reviews: very rough drawings, and somewhat inconsistent labeling. However, with my professor's repeated encouragement, I stuck with this book, and I'm glad I did. It outlines a method of machine-like construction that I have found invaluable for illustration, life drawing, and animation.
The idea of breaking down the human figure into simple forms for construction is not new - most good figure books I've come across outline methods of doing this. (One of the other reviews suggests Andrew Loomis, for example, which everyone should definitely check out.) What makes this book unique, though, is that it takes the principle a deeper extreme - you learn how to construct not only the basic masses (rib cage, legs, head, etc) but the individual bone and muscle groups that they are made out of. Solid drawing taken to a new level.
The loose, simplified style of the illustrations is necessary, I think - they capture the bare essense without any distracting detail. They also demonstrate how dynamic a drawing becomes when it is not overworked. On the other hand, they can be hard to "read" if you have no idea what you're looking at, so I think a companion book is necessary as a counterpoint for beginners like myself. My recommendation would be Dr. Paul Richer's "Artistic Anatomy," whose diagrams are the exact opposite of Bridgman's - exhaustive in detail and clarity. Usually, I have the two books open side by side - Bridgman for construction, Richer for clarification. Andrew Loomis is another must - very clear, very accessible. His system of construction is simpler, but as a result it is great for gesture drawing.
Bottom line, this book can be challenging in places, but it is well worth it to puzzle through them.