I really love my little IIIF; It is a pig to load, the squinty finder is only framed for one lens, no parallax compensation, a unusual speed setting system, and then there are the thread mount lenses. Speaking of lenses; you will find that most of the Leitz lenses you will find will be at least as old as the camera and have questionable glass.

If these aren't good enough reasons for snapping up a nice Barnack then I don't know what else would convince you.