In case it is not clear from the sample photos on the app store, this app does not give a simple flipped image. It splits the screen and puts a flipped version side by side with the original. There are several options to let you fool around with the halves. But if there is just a direct full image flip it was not obvious.
Deleting 5 minutes after DL. One star because there is no option for zero.
monk1010 about Flipper - Mirror Image Editor, v1.4