It sounds like you've got a handle on how to manipulate sounds. My comment is more on the musical side...the song just doesn't go anywhere. It sounds like the same riff played with 20 different voices, which makes it become uninteresting.
Try coming up with a melody to go over the riff. Whether played or sung, that will give the listener some to focus on. It might also lead you to some possible changes to add to the chord progression.
Think of it this way, would Smoke On The Water have been a hit if it was just "dum dum dum....dum dum da dum" for 4 minutes without the words and melody?