Google Maps is known for its accuracy, particularly in the United States. However, in extremely rural and sparsely populated areas, that accuracy may drop slightly due to the low number of people reviewing and correcting that data.
West Virginia is a generally rural state, with few major population centers. Areas such as Charleston or Lewisburg, where the population density is higher, may have much higher accuracy in general than more rural areas. However, since Google Maps uses satellites as well as multiple forms of ground and air data collection for its map creation, even rural areas should be fairly accurate, and Google Maps should be usable for directions in those areas with minimal worry.