I've been working on this script for about a year now, but never really shared it anywhere -- (it's actually in the wiki but I never shared it anywhere that I could collect feedback from.) I'm trying to keep it as simple and as friendly as possible for being a command-line interface.

Up-to-date documentation is available on GitHub along with binary and source downloads.
https://github.com/Wulfre/e621dl

If you bother going back through the commits or releases, you can see that I make a lot of significant -- (and tiny, insignificant) -- changes. I'm completely open to suggestions, general feedback, and the like; even for little details.