It's simple but it works. The graphics are oldschool and minimalistic, but it's clear what everything is supposed to be, the animations are cute, and the "reflection" effect is really neat. I struggled a bit at first until I figured out the timings and your attack range.
The only thing that's really missing is a lives/health indicator- I made it to Wave 3 my first time around before getting sent back to Wave 1 but I wasn't sure if this was because I got hit too many times or if that was just the end of the game until I tried it again.