Maps are one of hte commonest kind of information graphic. They occur in many forms, in many contexts, and commonly carry more data per square inch than just about any other kind of diagram. Also, a map carries some sense of authority and may even inspire a kind of loyalty - surely you know at least one map fanatic? That carrying capacity and authority can be used badly as easily as used well: incompetently, to make some point at the expense of others, or intentionally to misdirect.
The book's first section reminds us that every map contains mis- or missing information - if only because the world is round and the map is flat. Later, Mommonier gives examples of incompetence showing how information, especially in color, can be illegible.
He also shows how maps can affect political decisions as close as your own back yard, the maps used to make land planning and zoning decisions. He works up from town hall politics to the international scale, including some remarkable Cold War artifacts. He mentions esthetics only briefly, mostly to point out how the decision to make a map look nice can corrupt its data content. This is a loss since esthetics don't inherently conflict with the message, but good illustrators already know how to create visual appeal and bad ones should not be encouraged.
This is a useful addition for anyone who creates or uses information in picture form. It's not as broad as other books, but adds depth to discussions about one particular kind of information graphic. The wide ranging and well categorized bibliography is just an extra.
//wiredweird