Photoshop Touch received an update adding the much needed support for Retina and higher resolution images – up to 12 megapixel, which should fulfill your mobile camera image needs. What is even more remarkable is the improved performance of the UI, taking advantage of GPU acceleration. To learn more about how to support Retina displays in your application, read the Retina for Adobe AIR applications guide.
The complete list of new features is on the official Adobe blog announcement.
Overall the user feedback for the new version is very positive, as user ratings indicate. A clear message how important visual enhancements such as Retina support are.