Hi guys, sorry for the delayed response on this! Have been seeing a number of reports about people having trouble backing it up or getting coins off the device. We are investigating a different approach to the app which will hopefully make it more reliable. I wish we could make progress on it faster, but it's still just a side project for the moment. As always, continue to treat it like a beta app and don't put any coins on the device you are unwilling to lose. Hope to have more info soon!
Btw, to answer the question about backing up. The wallet is stored on the devices internal memory, so I'm not aware of any way to backup this file with the standard usb cable connection etc. Hope it helps!