I played around with it a bit today. The interface could use a bit of work, but there are a lot of features. Features including the ability to use photoshop plugins. That is one thing that I have found lacking in any alternatives to date.
I'm very intrigued by it as a Mac and PS user. There are apparently some things very much still in development while the Beta is out. This is a good little overview of what it does and doesn't quite do yet.
