So I have been playing with Back Country Navigator for Android on my Samsung Galaxy SIII
It works... it's a bit wonky to configure and use but it works.
I had to install the Accuterra maps which cost another $40 but these are the shaded topo maps which I really like. They're similar to the National Geographic shaded maps that I'm sure we are all familiar with.
Being able to easily zoom in and out similar to Google Maps is going to be VERY handy.
It works offline so what you have to do is select a rectangle of space and trigger it for downloading offline.
I think Yosemite National Park was about 400MB. So not too bad.
I went ahead and purchased an SD card though and it now stores most of my podcasts, movies, etc.
I couldn't figure out a way to move the map tile data to the SD card though which kind of sucks.
I went through and navigated through Yosemite where I had backpacked in the past. Everything worked like a charm in the main interface.
I carry a phone ANYWAY for movies, books, music, photos, and videos so it doesn't add any extra weight. If you compare it vs a $300-700 Garmin GPS device it's a CLEAR winner.
Has anyone here used a Garmin GPS device vs Back Country Navigator? I'd love to see how they compare.