In testing this app, I found crashers when applying filters to single layer JPEGs, and also found inoperative or incomplete features. Example: the color picker has no option for pixel values and does not work with the HSB color mode.
For $79 the application should be a lot more polished than this IMO. I like the idea of putting core editing tools inside an Aperture-like UI (much better concept than Pixelmator which is a total mess of a UI), but it's only half-baked IMO.