Man of Steel is out and if you want to get your eyes pummelled with insane fight sequences, I suggest you watch it. But what if Superman actually wanted to pummel your face instead? What would a punch by Superman feel like? A lot worse than even getting punched by Mike Tyson.
If Superman's fist was 300g and he could move at 99% the speed of light, his punch would be cable of punching at an energy 190,000,000,000,000,000 joules. That's quadrillion. That's 45 megatonnes of TNT. That's 2,800 times more powerful than Hiroshima. The temperature of his punch would be 79,999,999,999,726.9 degrees Celsius. Earth has never seen such power. Oh and you'd be completely destroyed at an atomic level.