-The hit box is ridiculous.
Agree with that, even for an oldschool shooter.
-mandatory hits (Any good shmup does not force you to get hit).
I really don't see what you mean.
-being stuck in a wall leads to instant death (other GOOD shooters make you invincible, so you can pass through the wall).
This is quite common in oldschool shooters featuring walls.
-you speed down when your hit! (Good luck at the final boss)
Very common thing.
-They do not heal you after you beat a level.
Quite common even though I agree it's frustrating.
-Some weapons do NOT hurt the boss, unless you in a specific position.
You mean the bombs? Of course you have to hit the target, it's aprt of the gameplay. The game makes you get near the bosses in order to be able to beat them. I don't see what's wrong with that.