Hey! I remember you game!
The controls are fine, I think maybe the player character should accelerate to a slightly higher top speed.
I would love to have a little dash, or a dodge roll (see enter the gungeon for a top down example).
The level designs were quite good, I'd juice them up with more incidental breakable stuff in them that keeps the axe bouncing: think computer consoles, pipes that blast out steam which hurts enemies (and you!) when broken, etc. etc.