A few annoyances, like no autosave, how its hard to select the actual ball sometimes (like it doesn't register clicks or something) make it a so so game.
Waaayyy too fucking tedious with equipment micromanagement. For playabilty sake, you should just pretend we have a bag of holding and allow infinite equipment capacity.
If you know the trick to beat the boss, its pretty easy. You first avoid him once (go upper left) and then just go in a left motion to dodge/shoot him and then go in a right to dodge/shoot him and just keep on doing that until he's dead.