Looks really nice. Good options page. Flexible, customizable, easy to integrate into a theme with post attachments scattered here and there.
It throws a bunch of warnings when you save the settings. It's surprising and spawns emails from clients, but it still works. I tried changing the Grouping Labels to no avail. I want to remove "Image" from the beginning of the string, but it won't take a blank value. Entered other values, but "Image" is still displayed on the site.