The cover proudly proclaims that John Bear is the "first person to ever write a doctoral dissertation on complaining"; this book grew out of that dissertation.
There is a lot of data about the effect of different kinds of complaints (such as the lack of effectiveness of most mass letter writing campaigns), stuff on how companies respond to complaints, some Tom Peters-esque stuff on how they should respond, and a "common sense" chapter on how to reduce the times you find yourself in a situation where you need to complain. (The data and advice is almost totally US-centric.)
The sprinkling of "case studies" of actual complaints adds a little spice (especially in the "creative revenge" section), but the data sections are a little repetitive, and the overall message could probably be summarised in a five page pamphlet.