Cute game, I really like the art (especially the sprite-work), feels fun to control and as a big fan of the classic-style Castlevanias I'll definitely play through it all when I have more time.
Only issues I've found are general performance issues (which is fine since it's a black and white GameBoy game) and a glitch where invincibility frames carry over permanently upon screen transitions (I assume due to not setting the i-frame variable to be off at the start of a new scene) but overall a really good and impressive effort.