I like the powerups and and artstyle, though I needed to have it in full screen in order to fully appreciate the pixel art. There was a lot of lag when starting from the title screen, at the start of the first run and then in later runs. There is a tendency for lag to occur when taking multiple hits.
I like the little animations that occurs in the character portrait when collecting powerups or taking damage. A possible UI improvement would be to have the enemy health bar always be on-screen, as it would make it easier to determine why the game has ended
I had a minor issue with determining what counts towards the "accuracy" criteria for scoring, as I initially thought that only my sword swipes counted towards it. I was surprised to learn that the reflected attacks counted as my own attack and also counted towards my accuracy. More scoring criteria could cause variation in a player's strategy. For example, time bonus for faster kills; no-hit bonuses; sword-only or reflection only bonuses; No powerup runs (this might not be feasible in the game's current state)
A bullet-hell game with ratcheting difficulty.