I find it pretty quirky, but I'm trying to move the sites I manage over to the Radiant content management system. Additional functionality is provided through extensions and plugins, and I've extended a couple to do some things that I need:
page_attachments - a text description field for each attachment. You can't currently edit the description.
database_form - the ability to upload files along with forms (not yet any way to view them, but I'll extend the admin thing soon)