I had fun with this. I wasn't able to beat it, but the power-ups feel really good and worthwhile.
When the enemies got very fast it was really hard to kite them without taking damage. I think it was because I'm looking behind me most of the time (to take care of the pile-up that is chasing me), and they get fast enough to sneak in where I'm not looking. They don't make any noise, so the only way for me to tell one is nearby is to whip the camera around a whole lot.