fretless warr guitar

I haven't yet picked up King Crimson's latest EP, "Happy with what you have to be happy with;" however, something on the back cover caught my eye. Apparently Trey Gunn is now playing fretless warr guitar. Is it just me or does that not sound like the hardest instrument to play ever. I don't play guitar, much less warr guitar, but it seems pretty damn difficult to me for some one to be able to finger tap on a fretless instrument. By the way, has anyone picked up this EP--is it worth it? andy