This is the only movie that I know of where DeNiro and Pacino actually share a scene. It's worth buying just for that scene in the diner alone. However, the movie is great on many levels including the superb supporting cast. You cannot go wrong buying this one.
Okay, the best of their movie would be the Godfather II, but they did not intersect in that movie. In this movie they delivered it well. You would think Al Pacino would be the bad guy and Robert DeNiro the good guy but it was the other way round. I'd prefer Al Pacino to be the bad guy, he did it so well in Godfather I & II. It's just a movie, it's not a true story, so the review shouldn't be that deep. The acting was great.