I agree with Jeff. It is impossible to like a character such as Dean, with a dark background and villainous lifestyle. It is even more difficult to understand why Sal, an intellectual, would want Dean as a friend. However, as the story continues, it is easy to see that Sal is feeling depressed, and that he wants to find someone who will teach him the ways of a more exhilarating life.

Inversely, it seems as though Dean is looking towards Sal as a way to settle down. We see this is not the case when Dean finds a new girlfriend, Camille, and continues his crazy life.