The intro cutscene is great!
The fight itself has a steep curve I think, I couldn't make it past the second phase. I would love to have some damage indicators on the boss, other than the healthbar on top, which tbh I'm not really focusing at. I'd also like it if the boss itself would move too or if there were some obstacles in the level, but maybe that's part of a higher phase which I didn't get to. The UI looks great!
The audio was okay I think, but a little bland compared to the rest. It also stopped playing randomly after I lost one time.