Cool game.
1, When you shoot, the shoot sound becomes quit for a while.
2, The game is very hard, maybe you should tone down the enemies or add a health system.
3, The game is more about shooting then dodging. Maybe shooting can be a powerup., but not a main mechanic.
4, The screen shake can get a bit annoying at times. Maybe you should make a switch or something to turn on and off the screen shake.
Other then that. Cool game.