A lot of people joke that his artwork is sub-par and the music is repetitive, but frankly... the integration of all three into a single product / series of games is pretty amazing.
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I don't know if gaming is the "ultimate" form of art. And no one is going to say that Zun's art or music is the best in the world.
But the fact that Zun can do all three and have them play off each other in his games is pretty masterful. There's a big difference in feel between people who only have mastered say Programming, but rely upon a team-member to do the art and/or music.
Having the sound-effects integrate into your musical scores (thanks to understanding music theory / beats), as well as generating artwork from programmatic features (the pretty "bullet patterns" of Zun's games) is pretty unique. https://www.youtube.com/watch?v=s8JmfCYmtHo
Zun can make bullet patterns that look beautiful, while simultaneously is fun to dodge / play with, and with sound effects that integrate well into the music.