Planning my camping trip to GA last week I knew my route would have me outside of T-Mobile data service for a good portion of the trip. So I hit Google to figure out how to use Google Maps in an offline mode.
You can't do that. It's not a supported feature. You can download maps, but turn-by-turn navigation is not supported. So my next thought was to check out Open Street Maps apps for Android.
With that many choices and limited time to investigate, I downloaded one that locked up my phone (can't remember which one it was,) then my 2nd try was Navigator by mapFactor. It's a commercial product with a paid version that uses TomTom data, and a free version that uses OSM data. One really cool feature is that you don't have to burn up a lot of your phone's storage with maps you don't need. You can pick and choose by state which maps to download.
The app was flawless on the trip. Turn-by-turn directions were just as good as Google, and the speed limit data was spot on for most of the trip. I did turn off the exceeding speed limit warnings though. They were annoying. The interface to input your destination is a little clunky, definitely not as elegant as Google. But that is a small price to pay to have turn-by-navigation services in the remote mountains of NC and GA. It also has traffic camera locations.
The routing preferences were much more detailed than Google. The app categorizes roads in a variety of ways (all sort of European) and you can exclude roads such as "local" or "small local" from navigation. You an also exclude ferries, although I now sort of want it to send me somewhere that involves a ferry. Google has sent me down some farm roads in rural VA when it thought the speed limit was 55 on a road where 25 was barely possible. The voice for directions is a delightful British female voice, who instead of saying "continue straight" says "carry on," which I found way more delightful than is probably justified.
Overall, I'm very impressed. It doesn't have live traffic data, but it's probably only a matter of time before somebody figures out an open source solution to that. Google may be better around town where you have good data access, but Navigator Free (and probably 20 of the other options) are great backups when you venture off the interstate highways.