Yeah, the original is one of the greatest action movies ever made (and one of my favorite movies in any genre). It is rife with tension and suspense. And it also features sharp writing and superb acting. Walter Matthau, Robert Shaw, Martin Balsam, and Jerry Stiller, in particular, are at their peak.
The main reason I've always enjoyed it is because it creates excitement without employing all of the typical action-film cliches. Moreover, as you said Matt, it is really funny. I think it is one of the greatest films about New York City ever made.
With all that being said, I've considered dropping the money to see the second remake, just to see how much Tony Scott screwed it up. I remember the made-for-TV remake with Vincent D'Onofrio was quite bad. I imagine that this second theatrical version is probably just as poor.