My high score is 12. It get's really frantic the further you get because the black fuzzy enemies don't require you to move too much but when the red enemies with the guns appear it really ramps it up a notch.
I enjoyed trying to beat my score.
Just one thing I'd like to mention was that the more enemies are on the screen and the more enemies you're killing, the camera shake can give you a little bit of motion sickness if it's shaking all the time but it's not really problematic unless you get further.