I think it's popular because
- It's a quick read
- It takes place in New York and way too many people have a soft lovey spot for New York, they're looking for a novel that captures the "experience" and this is kind of one of them... the main character is totally at home in the city.
- It has teachers in it. Smart teachers that give good advice. High school reading assignments are assigned by... teachers. So there ya go.
Nice Guys think they're God's gift to women, it's just that women are mysterious outer space aliens who are too brainless to realize it. Holden constantly refers to women like they're another species, generalizing girls like crazy, complaining that it's so hard to know what they think. There are no confused, mind-game playing women in the whole book... every female character has pretty simple, clear motivations and Holden almost works to not understand them. It's insane. They're all kind and well-meaning, except the prostitute, but she's at least very obviously motivated by one thing (money). It's okay for Holden to be motivated only by self-pitying needyness but it's not okay for her to be motivated by money? Come on.
You could argue that it's okay to have a jerk of a central character if your other characters are good deep people... I don't agree. We're supposed to sympathize with central characters. Authors don't create central characters that you're not supposed to feel something for. In college, I knew all these "edgy" people who thought High Fidelity was such a great movie... it's not, it's horrible. John Cusack plays a self-centered woman-hater for the ages, but we're supposed to feel sorry for him because women don't flock to his penis like he thinks they should? He treats them terribly. I hate him.
So anyway now I can rest easy knowing that my memories about Catcher in the Rye are accurate, and not a result of the person I was in high school. It's just the person I am forever. If you want to read it just to say you did, I'd say go for it... it only takes a few days and it is a "classic" after all. But I don't think it'll really make you a better person.