Pretty good for a beta!
I would also like to see some improvement on the combat system. It's definitely got promise. Some animations for when you fire would be cool... and sound effects other than the walking ones would be cool. I would also recommend making it so the footsteps stop when you're moving in mid-air. It'd also be nice if the monsters were actually a threat... when I got to them, I could just sprint and jump on top of and over them. All in all, keep working on it. I like the graphics and all that, nice arcade/side-scrolling feel.