I have a Igills, and have had it lock up in compass mode on two dives and had to surface, undock the phone, restart the app to use it. The rep at Igills had me uninstall the app and reinstall it after the first time and I lost all of my previous dives. It still froze up on my next dive and they said they would check the app to see if happens on their end. Yesterday I did two dives and it got stuck in video mode, I could start and stop the video but could not get back to the computer mode. It did record the dive and I had no issues on the second dive.
When it works it is very nice. Pictures and video are great, the digital compass is easier to see than the one in my console , and the computer works as well as the one in my console also.