This app has been around for a year but is quite low-key despite its being the best art app on Android IMHO. In short, the app provides complex brush dynamics, custom brushes, shortcuts, hotkeys, pen pressure curve adjustment, almost all of blending modes for brushes and layers as seen in Photoshop etc. I'm simply a hobbyist painter but I believe the folks here would enjoy using this app as well.
(image taken from Play store)
* N.B.: the app itself costs ~$8. There is an extension which costs an addition 20 bucks, but frankly it offers no addition exclusive features (yet?) rather than UI improvement. To be fair, the UI improvement is really nice. There are additional panels (similar to those in the desktop applications) which you can move/show/hide/dock everywhere. It also remembers the workspace for portrait and landscape mode without messing up when changing from one to another. But $20.. yikes!
In the developer defense, he is an independent dev and is struggling with the low sale of the app. It also hit me when he indicated that people could spend $500 on a tablet, $30+ for a stylus or a case but strangely hesitate to pay the same for an app. Anyhow if you appreciate the app enough or want to buy the dev (more than) a beer, consider supporting him by purchasing the extension.
* Some helpful links: