GMXT can be used anywhere, does turn-by-turn navigation, stores location of contacts in Outlook, and needn't use an internet connection. Very similar to a dedicated gps. You pay once for the (maps) licence.
Google maps, Bing mobile and others like Beeline and NoniGPSPlot require an internet connection. You pay for the data link.
If you're anything more than an occasional ad hoc user, get GMXT or TomTom.