I like it :)
I've only spent a few hours using it, so take my comments with a grain of salt...or maybe one of those salt licks.
The cropping shadow is fantastic. I don't know what it's really called, but it darkens parts of the image outside of the current cropping area. It makes it really easy to see what's in, and what's out.
Preview on the unsharp mask filter - thank you thank you thank you!
I started fooling around with the Channel Mixer filter, I would like a way to zoom in / out of the preview as well as panning...A simple way to enlarge it would be great too.