Does it work with no phone signal? Coverage in the Pyrenées is pretty good, and there were a couple of times when we'd got off the path and found geo-location useful (the French IGN mapping system is very good and free). But there were other times where it was unusable.
Obviously we had a paper map and compass. It's never safe in the wilds without one.
Even the best phone map doesn't extend far enough at once to pinpoint landmarks, for example.
@mappingsupport
Also, never assume that a person is capable of reading a map.