iPiccy is the first of three photo programs I have tried. Out of the three, I like it the best. There are so many different aspects to it that even after six months of using it, I am still finding cool things to do and ways to enhance photos.
If you want just the basics - brighten, sharpen and crop - they are easy to find and to do. If you want more advanced enhancements, there is an endless supply of combinations of things you can do to turn a blah photo into a masterpiece.