UKMap is a highly detailed, feature rich mapping database, which comprises integrated map layers and attribute tables. Captured for use at 1:1,000 scale, UKMap includes buildings with 3D information, road detail including pavements, lane markings, pedestrian crossings and speed humps, a full address gazetteer, inferred property boundaries, land use coding and a wide range of points of interest. It also includes aerial photography and terrain layers.
So whilst there may be a cost, this level of detail could be ideal as a base for an urban street map.
It is also going to be a while before all the maps are available, but anything that competes with the OS and removes the monopoly they currently hold must be a good thing.