I think it’s one of those books that people like more when it’s not forced on them. If the book was assigned to you in high school the message may have been lost on you as you weren’t at that point in your life yet, or you were and like Holden you were running away from confronting it. Without that core bit of information Holden comes across as a pretty non-sympathetic protagonist; which is why I think a lot of people hated him. For the entirety of the story Holden is reaching out to characters just to listen to him and if you aren’t in the mood to listen to him you’re going to get fed up with the book.