I have absolutely no qualms about revealing this spoiler, because Spiderman III is one of the worst movies I have ever seen, and now I have saved you the trouble of seeing it.
By the end of that movie, you hate every single character, except for Harry. He starts out being kind of a jackass, but, hey, his father's dead, cut him some slack. And, listen closely, because this is the important part, he redeems himself totally and in every way.
You know who starts out a jackass in that movie and then stays a jackass? That's right, Peter Parker, I'm looking at you.
We're not supposed to like Harry from the beginning, because he's good-looking and rich and MJ likes him instead of Peter. Well, um, I don't buy that. I too would like Harry instead of Peter, because Peter is a weirdo with an annoying voice and massive latent jackassery. The only possible way to make Peter more appealing than Harry is to kill Harry.
I would suggest, screen-writers, that you make characters who are supposed to be appealing actually appealing, instead of just killing off everyone likable so that MJ picks Peter by default. In fact, kill everyone but Harry, because they're all jerks. I'd totally watch Green Goblin Junior: Actually, Spiderman IS a Jerk.