The original "show about nothing" Just watched Diner for the second time (first in many years) and again enjoyed it very much. The script and performances are very well done, and the piece has a truly lived in feel to it. What is most interesting, however, is how the movie prefigures so much of what passes now for originality in cinema. Consider the sandwich argument and then think of Jerry, George, and Kramer sitting in their own "diner." This movie is a kind of primer on contemporary "friendship" stories featuring ensemble casts. Think: "Beautiful Girls," "Friends," "The Big Chill," "Kicking and Screaming," "Metropolitan," to name just a few of the successes. In fact, I think it's possible that it's impact might be dating the film somewhat: let's face it, the diner dialogue schtick has been copied so many times now (with hugely mixed results) that I think newcomers to Levinson's original may not be as impressed/surprised. Hopefully, this isn't the case, as there are still some special moments here.
One other thought I had was that this may also be a fundamentally "guy" movie. It seems to focus very specifically on how young men often relate to each other and to problems associated with a particular time in life: call it the "rat pack" mentality. I'm not sure how many women will identify as readily with these relationships.
PS: The DVD has a neat "making of" documentary which gives some nice insight into how Levinson fostered a real sense of camraderie between his young actors, which definitely shows onscreen. Also definitely check out "Avalon," Levinson's more mature and sweeping portrayal of Baltimore, the immigrant experience, and the American Dream.