Pretty good. My only issue is that the third boss spawns the cars a bit too quickly to react, especially near the end of the fight where you have all the other bullets to avoid (I happened to be right next to where the car was about to spawn and got hit). I also think the dash move could've been better introduced in the first fight (with something like the fourth boss's bullet walls) since I thought I was stuck in the corner during the second boss, but I figured it out after a couple deaths.
If you're gonna make another game like this, would you be willing to swap the health bar for more frequent checkpoints? I'm okay with one hit deaths, but having to redo the first half of the fight each time I die on the second half is kinda tedious.
Again, everything else is done well, and I liked it overall.
P.S. Where can I get the music?