Passable, but not enjoyable.
I'm really hung up on the poor collision detection. Instead of looking for contact with the actual enemy sprites, the game looks for contact with their bounding boxes. Even when you realize this, you can still mistime your movement and graze the invisible boundary.
Music was also not good. Frankly, that was the worst rendition of Sonic&Knuckles' Sky Sanctuary level music I've ever heard.