I really liked the way the upgrades integrate into the movement, and they felt really good to play around with!
The attack felt a bit weak and unresponsive, so that could be polished a bit. I liked the bosses, and the final boss was a nice way of closing the game.
The platforming also sometimes felt a bit too tight, almost like you weren't supposed to be able to reach some places and you bugged your way up there.
But overall an enjoyable game, good job!