Well done, love the effects and screenshake. It feels pretty polished.
It took me a few tries to get the hang of it, but once I did I was able to survive for a little while and rack up a decent score. It has that 'one more try' feel especially since it's so easy to hop back into another attempt.
My only suggestion would be to make it so enemies wait a second to shoot once they've spawned. It feels a bit unfair when an enemy spawns and shoots me before I have time to react.