I've bought one to give it a go, the smaller Duo Realis model 80 as I recall.
It is a finesse presentation using a hard bait, really, for suspended fish at various depths. If you find bass on your electronics, say in 15' of water, you can calculate the fall rate and the time it takes to drop down that deep, cast a bit beyond your target area, then a very slow retrieval.
It's another "Japanese imported idea" from what I have read and heard where they fish in very crowded waters so they devlop a lot of finesse applications to slow down and nab fish.
I suppose it might be a good lure to toss into a boil of schooling bass, too.