I have National Geographic Topo State Series for both CA and VA but use other programs for most of my mapping. I make maps for a living and so I use some more professional products (ArcGIS) and some that I have used for a while (Keyhole/Google Earth). The NG program has some useful features so I use that at times. I have used the Delorme program and found it useful as well. It comes with a larger dataset and is thus cheaper where as the NG program is state/region based and costs more for the same coverage. The datasets on both have mistakes but so do all map datasets.

USGS has pushed the infallibility of maps for so long that we have come to absolutely trust maps, however, people are now using maps more so they find a lot more mistakes. Many errors come from localities built roads according to the topography while the maps show the prior planned routes. Many errors existed on the old paper topo maps and the errors were carried over to the new digital datasets when they were digitized. Additionally, a lot of that paper to digital transfer was performed by interns for the USGS. Interns make a lot of mistakes. Even with a small error rate many errors will show up simply because of the massive amount of roads. There are other problems with mapping software and paper maps too- often the same mistake is not shared between different map types (e.g. topographic and street). So checking between two different map types is often helpful.