I will be the first to admit that I don't have the greatest sense of direction. There have been several embarrassing situations when I have gotten lost when I really should have known where I was going. Due to these experiences I use maps applications on my phone both when I travel and also when I am exploring unfamiliar parts of the city.
Since I am an iPhone user I have the standard Apple Maps application on my phone though I have also downloaded Google maps for iOS. I don't have any horror stories from the Apple maps application like others in the user community. The only reason I switched is that Apple maps does not support mass transit directions natively and I am a regular mass transit rider. (The Apple maps will point you toward another app though that is one more unnecessary step.) Though while the Google Maps app does have great functionality I do prefer the UI on the Apple maps application (and the also the ability to spin the map in the Apple version.)
Other than maps I don't use geo location services like Four Square or Latitude. Though I think there could be great value in these services for public or academic libraries as an engagement tool.