Nice prototype! The music is really cool and really sets the right mood for some frenetic shooting action!
Concerning game feel, everything is still in its early stages but I think you are going in the right direction. For example, I would suggest adding a crosshair so I know exactly where I am shooting. Also its not clear if the enemy pickups are useful for something. Do they give me health? Score? Or is it just placeholder?
Keep making games! :D