OpenStreetMap (OSM) and Google Maps (GMaps) each have their strengths and weaknesses (have a look at GIS.stackexchange.com’s recent discussion on this). Probably the biggest advantage for us is that OSM can be edited quickly, and the road data used directly (download to GPS or for your GIS system directly). Click below to read more.
Compare it to the OpenStreetMap data for the same area (second map). I had an afternoon free waiting at the Nkasi district offices and quickly put this together with GPS and some satellite imagery. All it needs is for someone to add the street names and some buildings and it starts to look really good.
Another great example of developing OSM data: the “Map Tandale” project in Dar es Salaam (with google maps comparison here).
Of course, that’s not always the case … here’s the same area in Njiro, where the community’s done work in Google Mapmaker and we’ve not done much in OSM (yet!):
If you want to compare map data for the same area, http://sautter.com/map/ lets you do transparent overlays of OSM over the top of Gmaps, Yahoo and others.