Really nice graphics and animations, liked the little amount of sounds it had too. Game looks really polished.for an early demo.
Physics take some time to get used to but they aren't bad either. As Wur said you need to add something that shows the player how and where the shooting and floor breaking mechanics work, at least the first time you need to use them. I liked the boss that jumps and damages you when he lands, but he also needs to introduce that mechanic to the player before the fight actually starts, so you don't lose a hit while figuring out what to do.
Hope to see more updates on this soon.