Not bad! I'm a huge Mega Man fan so forgive me for being a bit critical of your game. Let's start with the good stuff. The sounds and graphics fit well together and I really appreciate the lenient checkpoints. The level design is not bad at all and because of how small your character is, you have a lot of room to see and predict what's coming next.
The game play itself felt a bit off and I really didn't like the fact that you can't move forward while shooting. Jumping was okay and timing your shots mid-jump was solid. I tried to figure out how the knock back worked. It felt almost as if the speed in which you were moving forward while being hit was also the speed at which you were knocked back, rather than a set distance each time.
Overall, it was fun to play and a pretty quick run through. One thing I tried doing on my second play through was speed running it and although the game "flow" isn't optimal, it wasn't awful as well, so good job on that.