Even after the first few times, I still jumped when a headcrab leaped at me and panicked as I emptied a clip at it to make sure it didn't go again. Breathless and brilliant.
I still panic when reloading when under attack. Under pressure it's easy to fumble the reload, either forgetting to release the clip, dropping the new one or forgetting to prime the gun. So much more intense than reloading in pancake games.