I saw the movie prior to reading the book. Normally, I'd prefer to read the book first, but in this case I think I was much more satisfied having watched the movie before reading the book.

I didn't expect all the sub-stories and backgrounds that were presented in the novel. If I had read the novel first, I probably would have expected to see a lot of stories acted out, that ended up not making it into the film (Bocciccios, Paulie/Boxers).