If it kills you, I don't know about "100 times worse". More like a game freeze.

Being punched in the face, in a fight, doesn't feel like anything, due to all the adrenaline. It's disorienting and involves visual flashes, but it's more like getting suddenly drunk. A lot of people aren't aware of how many hits they're taking at the time.

If you're conscious afterward, it's no fun. If a guy's on top of you and keeps beating the shit out of you, you may panic (even though there's little pain) because, at that point, you're probably in no shape to fight back and it's up to him whether you die. And, as always after a serious fight, waking up the next day is going to be a bitch.

In a one-punch kill, though, there's no "after"... at least, not in the known physical world.