I deleted this thread from the Planes, Trains and Automobiles thread. Although it fits there, it also fits here - and we don't want to have 2 separate discussions going on at the same time on the same topic.
Cul-de-sacs are good and bad. If properly designed, and part of an overall subdivision plan that still maintains good access to the street grid, and to potential future development, they work - and as gkmo said, people want'em. But a subdivision consisting wholly of cul-de-sacs off a single looping collector, with limited access, no pedestrian links, and which cuts off potential links to future development they can really be a horrible form of development.
As in anything, balance is the key.