Phone apps

I already have the happy prospector and geo maps but was recently advised of a great offline app called Australian geological travelers maps.
Seems to have every overlay required at the click of a download whilst online then use in aeroplane mode. About 50 bucks to get downloaded and registered then a small Anual fee to maintain tenement updates etc.
Defiantly best one I have used so far. Easy and great geo detail. You can also use simple geo for tracks, wells etc for access and can overlay with varying transparency mindex drill holes gold deposits and resources. Plus magnetic imagery and more. It's all overlayed on great satelite imagery where you can record your tracks and save as kml file for Google earth.
Anyone else used this app and how do you find itk
Cheers