The biggest mistake is to see this book as a defense of sprawl. Instead, the author shows how Edge Cities--conglomerations of buildings and grounds that often grow at major highway intersections--fulfill many of the same functions that traditional cities have served for thousands of years.
The Edge City ethos, however, is often suffused with an obsession for security and control, and automobile travel for access absolutely dominates all other modes. However, the principals of density, mobility, and human reaction to the built environment in the Edge City follow similar patterns as what others (Kay, Marshall, and Kunstler) have observed and advocated for traditional downtowns. That is to say that people like to be in built environments that have a degree of safety yet serendipity at the same time, and that people like the sight of nature but the convenience of quick access to resources to meet their needs. Edge Cities and traditional cities succeed when they can provide people these often contradictory things.
Garreau presents Edge City as a reaction to market forces (p. 222) that fulfills the needs for corporate workers (pp. 55-56) and corporations to gain large contiguous spaces for workers where "spontaneity has been utterly tamed" (p. 230). Edge Cities may frighten people because they have been built so quickly (pp. 413-414).
Garreau (p. 400) comments on the antagonism that environmentalists and urbanists who admire Paris or London may feel with developers of Edge Cities. He points that common ground may be found in the idea that everyone seeks a quality of life. Indeed, it seems to me Edge Cities can show what people value. Traditional downtowns may show how these values might be built in a more sustainable way.