I use Ballistics AE as well, but on my iPhone and iPad. Works fairly well. Not exactly the most intuitive piece of software I have used. It could handle the 'Target' portion of the app much better. One should be able to resize, drag, zoom in and out, rotate, reorient the measuring caliper, etc. Still, it is fairly well integrated with the other aspects of the program so it gets a thumbs up.
I just downloaded SubMOA for my iPhone last night and played with it for a while. All it does is target oriented, no ballistics. It too has a number of problems but a lot of my above complaints have been taken care of. In other respects it is a pain to use. It should have a heirachical menu to force you to do certain items such as general settings first (top level stuff like (measurement type [metric/Imperial], etc), then session specific settings next (distance, rifle, caliber, picture import, picture orientation, etc.), and finally shot placement, calculations, etc. As it sits, it just runs without checking anything and either gives garbage in, garbage out type results, erases everything done without saving anything, or sometimes crashes. If one follows the magic sequence and inputs everything properly it seems to work well. There are no options to edit data other than to erase shot placements individually and if you do so after doing any of the calculation steps, (stepping out of the unknown magic sequence) none of the data is useful as it is NOT recalculated/replaced on the output screen. Bottom line is that if you plan on changing anything, erase/delete everything and start over. With some work to clean this up, this could be an excellent app.