For some people, another smartphone-only app they can use is RunGo: http://www.rungoapp.com
The RunGo webpage says it does for runners what in-car GPS does for drivers, and that’s exactly what it does: voice-directed navigation without having to look at the app display at all. I was quite startled when I was running a 50 mile ultra last year, 5,000+ feet up on a trail just outside Mount Rainier Nat’l Park, and I heard a pleasant siri-like electronic voice say, “bear left at the intersection in 50 yards”. It turned out a guy just behind me was using the RunGo app, and it did indeed appear to perform as advertised.
This sort of app can of course work only if you have a predefined route that you’re following. You can design a GPS track yourself on a PC and transfer it to use on your smartphone, or download a GPS route that someone else has created or that is a track of an actual route they took. RunGo also has some predefined routes on its website, I think, that may have more features.
I’m just throwing RunGo out there as another possible advantage of a smartphone. I can understand that some people would not want to use an app like RunGo, the electronic voice sounds out of place in the wilderness and it dumbifies navigation even more than just using a basic GPS device. But there are undeniable advantages. First, since it’s voice based you don’t need to divert attention to a device display, don’t need to worry about sunlight making display unreadable. Second, you don’t have to have your smartphone in your hand to use the app at all, the fellow I saw using it had it on his back in a pocket in his backpack.