Nice song
As a post below me said, a great base for a song.
But as a frequent drawer (wastes free tiem easily) I understand the 'unfinished' feeling, I get it all the time. When I get the unfinished feeling, I just keep rawing until I can't think of anything to add, and the people around me can't think of anything (decent) either.
You can always go back to a song easier than I can go back to a picture, partly because yours are on the computer and mine are on paper :P That and my style changes over time so I'd kinda get half a pic with one style and another half with a diff. style.