Tough but Fun
The game lets you throw punches to the stomach, face, and star punches. Each fight features a unique character to face off against, some of which you see twice. Fights last 3, 3 minute rounds.
The first league is pretty straight forwards. The second league gets a lot more challenging with opponents throwing harder punches and performing special moves that you'll have to figure out how to beat.
Graphics are decent for NES and don't need to be much better because it's more focused on the fight.
Iron Mikes is extremely hard to beat and you won't get any help from your referee, Mario.
But overall Punch Out is a great classic and it is worth sitting down and playing through at least once.