I usually don't rewatch movies as to me the plot is usually one of the most important aspects of a movie. Well, of course, this is move is an exception.
I have never read the book, so I went into watching this movie with no particular expectation. And it touches me in so many ways. Each character has their own struggles, and however unique they may be, everyone can relate to in one way or another. But what is most important to me is that it teaches me to learn the importance of noticing. It is easy for us to focus on our own problems, and not realizing that others might go through something similar, or that they might need our help as well. That's what Charlie is throughout the whole movie - a wallflower. He notices everyone's struggle, desire, and becomes their friend. As yet, there is not much attention on Charlie, until the very end of the movie where we see the story unfolds.
You just can't miss this movie. You just can't.