Yeah, they blew my mind when I first saw this technique. They are fun to do, and not too difficult if you've got panorama stitching software and Photoshop.
Yeah, I think I understand how you did it and could probably do it if I wanted to. I just end up at too many places where what's in front of me can be pretty interesting, but what's behind me... not so much. Not necessarily worth a panorama shot.