Hey, I know it has been 4 months since you release this game, but you and I just talked yesterday and I decided to finish this game.
Let me tell you some things:
Graphics: For graphics, I think your pixel art skills are AWESOME. The main character, the enemies, the bosses, they all have great sprites, I'd say almost professional.
However, some stuff was not in its right proportion. For example, the background, it seems to me it is resized, so it looks "not so nice". I believe if you fix these for future games, the pixel art will look perfect.
Gameplay: The gameplay needs to be improved. Sometimes I feel I don't have total control over the character, meaning the jumps and air movements were so "fixed" that you couldn't move your player with total freedom. In the second level, for example, there is a part where you need to jump from right to left, in between 2 ladders (there is a heart in the middle)... oh, it was frustrating hahaha. This is where I think I could help the most.
SFX and Music: SFX is not bad, but Music is not that good. I couldn't find a good melody that kept sounding my head.
Difficult: I think the difficulty is just perfect. Not too easy, and not too hard. I had some challenges when battling the bosses, but once you get the patterns, it is a little easier to kill them. I wouldn't change any part of this.
Overall I think the game is good, and I'm a big fan of your pixel art and design (the characters truly look nice!) =)
Hopefully, this helps you, don't take any comments in a bad way, I do believe honest feedback helps the most.
See ya!