Luminance is free for a limited time only in the App Store. The app’s regular price is just $0.99, but you can download it for free at the moment.
Luminance is a refined mini editing studio both for iPhone and iPad photographers. The app includes crop and rotation tools, several presets for instant photo enhancements and the possibility to customize effects through the manipulation of settings as hue and saturation, curves and levels, vignette, and so on.
Luminance will give you more flexibility than the greatest majority of editing apps without the complexity of the most comprehensive iOS editors. If you have yet to try the app, this is a good occasion to do so — Luminance is more than worth its full price, but if you want to try it, give this free download a go now.