I'm often underwhelmed by music visualizations. Generally, I find them distracting and somewhere on a continuum between unhelpful and pointless.
But
this visualization of a Chopin Fantasie-Impromptu is both fascinating and beautiful. I love the use of space and color, but what impresses me most is the subtle but effective animations around note-strikes and the fading of sound. But that's what I notice based on my background. I'm curious, what do other people see?