Right Layers pro edition.
It has great blender tools that work well. Its layer support are limited to 5 layers but shouldn't be too much of a problem, but still not the best out there. Brush choice is only ok, brushes has better selection, and Sketchbook & Art Studio do better pencil strokes.
Online community gallery is great idea but there are flaws to the implementation of it.
It has very good ink dropper tool which is quick to use on the fly.
The software is buggy and it has crashed on me twice. Account settings for example allow you to upload an avatar, except it doesn't work. Online gallery doesn't allow the uploaded to remove the drawing or painting, so there are many people who have uploaded multiple versions of the same file. Export is great as it let's you email with .psd layer info intact, however it does not allow you to upload the photo to something like flickr which would be more handy than a built in gallery that only people with the app and an iPad can see.
Overall a good App. Better than Art Studio, not as good as Sketchbook or Art Studio. Will upload an image later as I can not do it from the iPad directly due to it's software limitation.