The movie ends up being remembered far more for its unorthodox narrative structure than its actual narrative. I suppose that's fair, but as far as gimmicks go, it's an interesting one, and I was able to watch the movie again - knowing what happens - and enjoying it all the same.
I could've picked the "I'm chasing him/no, he's chasing me" part, because that part always makes me laugh. I could've gone with the ending/beginning. Instead, I went with Leonard and Natalie having a very uncivil disagreement.
"Find a pen"
Natalie's character has always been a bit...off. Finally, about halfway through the movie, the whole truth comes to light. She utterly despises Leonard, and is going to take personal pleasure in using his condition (has he told you about it?) for her own devices.
What happens after the punch is what makes the scene. Natalie calmly walks out to her car, as Leonard struggles to jot down the details what happened before his fleeting memory loses grip of them. The music underscoring the scene heightens the tension until... it's gone.