Its VERY double bass-ish - quite rich and thuddy sounding, not much treble, and the D/G strings really don't ring out, especially as you travel up towards the dusty end. I practiced the whole Rattlin Bone set last night and it really sounds the part.
If I wanted a modern hi-fi sounding fretless, then this really isn't it, in fact its miles away. But it is just great as a retro, low end instrument.