Great demo. I enjoyed it a lot. I love the visuals. Great character and generally effective animation.
I do think the ranged enemies are a bit tough. The movement supports bullet helly gameplay well. It might just be that the game is too short to build up that skill enough in players.
There are a few minor issues that you already know about probably. The spammable air attack trivializes the combat. Spamming roll and attack on the ground breaks the character controller sometimes. You can respawn inside the moving pillars in the central column area. Not really a problem since you have save load. The boss is a bit rough and very exploitable.