Just got this thing and have been finding my way...first thing, get a SD card for $35 and a SD card read/writer for $10 or so. Otherwise, it will take weeks to load the maps. I did load the maps provided that should cover the AT, PCT, and CDT. Then I dove into the maps and the trails were there, so that's good. Found the BMT too. I bet all the biggies are on this map.
It is a little goofy in that you have to turn off everything else running in your Windows version to get the map download to work. Instructions are provided that work. Probably more to follow as I dig into this thing and try to make it work.