Fun little game. I do like the visual and gameplay feel. It's fun to swing your arms. I wish there was some more swinging shenanigans. I do think though that the pace is a bit fast and the player is a bit big. A camera that pans further left or right based on direction would help. I also feel the controls are a little misleading for a GB game. Like A & B are both punches and 'start' is your jump button which doesn't make much sense. Probably condense the punches to alternate on one button and jump on the other. I didn't even know there was a jump button on spacebar at first as well.
But otherwise, I think it is visually fun. It's tough too and that as well has to do with player size. But I did beat it and get to the gold room at the top. I liked this!