I've published a new version of both TinyG for Android and TinyG for Android USB Service. This version cleans up the UI in a huge way, adds much better error checking/notification, and support for gcode downloads. I'll put up a new video when I have a few minutes, but I was able to use this version to do some real routing last week. It went through a small (660 line) gcode file without any troubles at all, and I expect it will work with arbitrarily large files since it operates a line at a time.
Let me know if you have any suggestions for improvements. I have a few in the hopper (long press for a continuous jog for example), but I'm going to be working on CAD designs and bug fixes for a while. I'm starting to design my solid body banjo prototype. More on that soon too.