It converts the standard (or extended) double bass from the slow, somewhat clumsy and awkward instrument that it is, to what amounts to a smaller (cuz it remains closed) easier to handle thing that actually works more like a Chromatic.
While I'm sure there will always be the "old schoolers" who continue to romanticize the old designs, I believe this new innovated bass attachment is probably destined to replace the bass harmonicas as we know them today. I know if I were a bass player, I'd be all over this thing.
Hey, what's not to like? It doesn't flop open and shut when you handle the thing. Guys don't hafta figure out where to put their big noses

when they play them. (mine kinda gets stuck between the two decks) The less "aesthetically challenged" players will be happy to know that their good lookin' faces can actually be seen by the audience. (and not be hidden by that upper deck) New numbers will be easier to learn. Even micing should be a lot easier with this new design.
@ge