That your first ever project? It's solid enough, I didn't encounter any gameplay-related issues, the collisions and controls work quite fine.
I have just a few things to say about the gameplay.
- Flandre's buttons.... Z and R? Why two keys that are far apart?
- Flandre didn't seem active when I get her to Defend or Attack. I think her contributions could stand to be more obvious-looking, or to activate way faster. (You see, in video games it's about showing that pressing buttons does make things happen)
- It's already been said but: Spacebar to shoot when you already have Arrow Keys to aim? You could really have just the Arrow Keys shoot.
- This too has been said below: It would be quite good to have feedback when something gets hit. Hit sound, or a sprite flashing, but both at once is best. (Yeah it's sitll about showing that something in the game registered and happened)
With that said, good efforts, especially on the boss battle.