Imagine a delay where every repeat gradually descends in pitch - it sounds like a nightmare, and that's the point.
"Lower regen settings sound like heavily vibrato'd delays across the 20ms-800ms range"
The Downward Spiral's pitch descent increases as you up the regen (aka feedback) control, right up to minutes of trails until the notes become a garbled mess.
Lower regen settings sound like heavily vibrato'd delays across the 20ms-800ms range, with the descent only apparent when you stop playing.
It's not the easiest to use creatively, but for adding a sense of derangement to any passage, it's a tortured treat.