The game is neat, reminds me of very old school master system games (the sega one, I don't remember it's alternate name) the controls are very responsive and it seems to fit the theme very well considering both the player and the boss don't really have a life bar or even lose much more than points when hitting each other.
The one problem I can point to is that in this kind of game shooting as often (and as fast) as possible feels like a must, so having to tap the shoot button for every shot to come out can be very tiring on the old trigger finger, to be able to hold down the fire button and shoot that way would be much better.