I know that it's a very well-respected novel. Don't know why I did not feel about it as deeply as most - my best attempt at self-analysis is that I intentionally did not let myself have any strong feelings about it. It would have been too painful to go back to real life and see that the vast majority of people around me were too self- serving to care about integrity or ethics.
Also, I might have read it too late - I think I was about 13 or 14 at the time, and at that point I was reading a lot of Theodore Dreiser - An American Tragedy, first and foremost, but also The Trilogy.