Very, very stylish! Also very difficult for me! I got to wave XIX at my best. The upgrade system is neat, getting one health back per fight is nice and it's fun to play.
For me the best upgrade is the stun, because the lunge from attacking usually gets me hit by any enemy who can't be one-shot. The damage increase didn't appear to do anything, at the point where I got it only two enemies took multiple hits (the shields and the dashers) and the dashers still took two hits afterward, which did me in. Maybe it's a random trigger?
The controls were a bit difficult for me, both the arrow keys option and WASD. I really wanted to play it with a controller, but that doesn't seem to be an option. It's tough to need to face enemies to attack without running into them, or letting them run into you, but I'm guessing that was an intentional difficulty choice. :)