Playing with an Xbox controller, it is much less ergonimic to have B be the shoot button, instead of X like pretty much every other action platformer. It would be great if there were an option to modify the button actions. Or else change to the standard A-jump X-shoot control scheme.
Yes, I plan to add customizable button mapping in a later update. Right now, you can also use the RB trigger button to shoot. I find it easier that way. I know it's not explained anywhere... I also plan on adding a better summary of the controls. :)