It's not bad. I think you've got a good start that could be expanded upon into something more detailed and interesting.
I agree with all the other comments and would also add that the character controls feel awfully "loose". If it were me, I'd keep the jump height the same, decrease jump speed, decrease gravity so the descent of the jump matches the ascent, increase the horizontal acceleration so the top horizontal speed is reached much more quickly, and decrease the top horizontal speed and bullet speed slightly.
I'd also suggest you use a lower-pitched sound effect for the shooting (or run a low-pass filter over it) because high pitched repeated sounds get annoying after awhile.
I think the camera shake would look fine if it were for a heavier weapon with a much lower rate of fire but for the faster weapon, it needs toned down.
Also, if you haven't already, could you please rate my team's game? I'd much appreciate it.