GPS reliability has been a controversial issue on the Ipad. Personally I only ever once lost a signal when I had a cover fitted to the ipad and not since I removed it for flying
Others have had trouble with the Ipad overheating and switching off, I haven't had that problem but with the unit on the yoke rather than on the screen and thus away from direct sunlight this is less likely,
Many use a separate GPS receiver to back up the one in the Ipad. Ie connected by blue tooth or plugged in to the socket of the ipad