I love 'em. I think they're a cool idea, and very environmentally sound. I'm going to pick one up and string it with an octave D so I can add a
soukous vibe when I'm recording overdubs.
I saw a documentary on BBC4 a few months ago which was about the Malagasy artist Hanitra Rasoanaivo and her band Tarika; in one scene, she was in a studio and one of the guitarists was playing an oil-can guitar with what looked like a Hamer neck. It sounded great playing traditional music with a
clean tone, but I don't think they would be suitable for metal, despite their construction. :P