Quite unreliable. Just finished a 7 hour hike. It stopped recording gps in the middle. There was no notification, so I hit resume an hour or so later and continued hiking. At the end I looked at the map. It had recorded the second part, so I hit save, it confirmed it finished saving. And now I have an empty activity...0km, 0 elevation, 0 calories burnt. For a paid app this is ridiculous and it is not the first time.