I'm amazed on what I can achieve on the iPhone - but I would say..hint, hint, we need more "brushes" and "textures" than we get from any application right now, including Paint.
Wish I had a "Oil painting" effect, or maybe, a Van Gogh "effect" - there's a lot more that can be done.
One thing to be aware of, my approach is try to go for feelings beyond the image. I'm impressed with so much good stuff I'm seeing here at CollectingSmiles - but remember, the work is meant to communicate beyond words - our goal is to say, as Artists, what can't be verbalized, but is known, internally.