So . . .dating sim X SHMUP as a full length game with this dynamic could be considered something of a dream to see I think.
For improvements other then just wanting more in general, sound effects as others have mentioned. Maybe a slight alteration of the ships design/hitbox to give you some area to graze in front of the cockpit to fit into some patterns better and maybe allow variations in ship speed for better fine control. (Most important for playing with keyboard)