OK, used it today in anger in the Lake District with no mobile coverage. It worked well but there are a couple of minor foibles:
1. It often seems to forget to load the maps and you have to zoom in and wait maybe 10-15secs for the maps to appear even though I’d only moved 1km since I last used it. This is on an iPhone 6, so no shortage of processor power. NB I don’t let it run in the background, so kill the app after checking my location and then relaunch it next time etc (to stop it draining the battery in the background).
2. The compass / direction arrow seemed pretty random, I’d prefer it if it just gave a dot for my location and I’ll use a real compass.
Way more handy than faffing with a proper map in a waterproof case etc when wandering round in the clag.