This book is interesting particularly for the evolution of direct marketing that Wunderman describes--and to a large degree, instigated. Readers will notice a tendency for Wunderman to toot his own horn, but don't worry; it doesn't ever become obnoxious.
The book would be good as a general guide as to what works and what doesn't--and why--in direct marketing. If a company is looking at direct marketing as a possible direction, this would be a good place to start to get an idea of what is involved, and what it takes to be successful. It may or may not help the reader that Wunderman describes using his techniques in marketing both goods (flowers) and services (credit cards).
In the end, you get more history from it than hard, specific tips. A very good read, but don't expect it to be "100 tips to direct marketing success". The hints are there, but you'll need to dig them out.