I've been following this guy for some time now, because visualizing music is sort of my pet passion. He's been printing rolls of MIDI visualizations since before I was born, and the idea was originally conceived back in 1974. So I guess he's my music visualization guitar hero.
My favorite part of the software is the way color is employed, and the circle of fifths color wheel. By just watching the songs on the wheel, like any circle of fifths, you'll be able to easily get the key of the song. But once you memorize the order of the color wheel, you can do it intuitively just by seeing the colors of the notes in the main visualization mode. In other words: with a little training, the extra dimension of color can be used to convey a whole different element of the music (the key) without having to add a circle of fifths to the screen. I can see extended use of this program inducing a sort of synesthesia in some people.