The character seems to fall a little too quickly. Then again, maybe that's the point? It could just be me not being used to seeing Mega Man struggling with gravity ;)
Some sound effects might be a little too loud, especially the stepping one. Having options to set the SFX volume .
I think the spear trap sprite blends in with the background a too well, I didn't immediately notice it popping out of the ground when triggered. For example, at 0:26, I feel it doesn't really stand out enough from the torch and skull pike.
The Mega Man sprite doesn't look too out of place to me, so I'd say you're definitely doing something right in the graphics department! He's just a placeholder, I'm assuming?