You just don't see visual effects like this in a 48 hour game jam. The only thing I might have liked changed is being able to see the time remaining right after getting killed instead of going straight to snow static so I have a sense of how far through the level I was.
At first I thought that an avoider game mechanic would be mediocre. Eventually I figured out that the key is not avoiding the enemies, but is killing them efficiently enough that they won't be able to swarm you, and that mental switch made for a good game. There might not be very much more room to expand on the concept, but it's great for a short game jam.
As for the music, maybe it's just me, but something seemed out of key on the last level with everything overlaid (probably the background synth, the one without the sweep/flanger).
The only semi-buggy thing I came across is that when you select the note for the final level, the mouse can be right over an enemy emitter when the stage starts so you end up being instantly killed.