I thought they might have been pretty smooth, surface wise. Never used them but am considering itThey are unique. They aren't entirely smooth like Chromes or Labella. I keep vollying between removing them and keeping them.
They do sound good, but they have a bit of a lumpy "tooth" to them. So the B, E, and A strings feel a bit strange. They are probably one of the easiest flatwounds to play, though. They are actually pretty lively for a flat-wound.