Bottom line: nothing works, because the main feature (selecting the part of the image you want to work on) does not work 90% of the time tried. With that in mind - it easier to use (and free of charge) to use iOS 5 picture editing. And if you really need to work seriously on a picture - use a Mac or or PC with Photoshop... This app is a waste of time to install. B.t.w. - thanks to German TV Galileo for your test of this app - a least I learnt now not to get apps recommended in your show!
Stahl152 about Feather retouch, v1.3