The bones here are really cool! the graphics are great, and I love the way the dialog box is set up. The font is a little hard to read and would have benefited from being pixel-perfect at this resolution, and it would have been nice to have a 1px black background around the life bar units to make those a little more legible too, I think.
The gun's fire rate and the amount of time you're locked in place feels really long, especially when you're trying to destroy a barrier. Similarly, if you fall off the bottom of the screen, it takes kind of a long time to die.
I do appreciate that enemy health doesn't reset when you die though! Overall a really solid entry, one of the most Game Boy games I've tried!