I like the arcade setting. It makes spend coins to buy something feel a lot more unique. Pac-Man as a choice of boss is very cool. The actual boss AI is quite nice; even though its simple, mixed with the environment its quite fun to dodge and weave while dealing with the kickback of your weapon.
Biggest complaint would be that the health bar was too high. Especially with the difficulty increase on the third phase, I think it would have been better if one could get their quicker.
SFX are nice, not distracting, good for the retro theme. The music is nice as well, also fits the retro theme well.
I like that you can shoot the arcade machines. The coins moving as things bump into them is also a neat addition.
Overall, a very nice entry.