Love the arena and setting with the audience all around and also the cutscenes were a pretty nice touch. I think you guys do a good job on the bosses, and I like how they seem to be interacting with the audience lol.
Some feedback that I would give is that when I first started the game, I spent a couple of minutes trying to figure out why I could not shoot my gun, but then I figured out that I had to refill the ammo. I think that it does help let the player know how to refill their ammo, but I would have loved a tutorial that went over the purpose of the ammo box before you put them in a boss fighting situation.
People have mentioned the bullet speed problem already, and as a fellow game developer, the problems are completely understandable due to time constraints.
In any case, good job on this entry!