VZNavigator is subscription based. And yes, as long as you get a GPS signal, it can locate you. But if you do not get a data/cell signal, it won't be able to load the maps.
If I were you, I would get the Geocaching app or buy a used unit like Hemorrhage suggested.
For non-geocaching, driving around directions, in the Google Maps app I have, there is a "Navigate" option (not to be confused with VZNavigator) that does vocal turn-based directions which is free. The icon looks like a blue arrow pointing up.