*possible spoilers*
Kevin Smith debut film is brilliant because it works on so many different levels. From budget limitations resulting in running gags -the closed shutters "explaining" the darkness on the store setting where in fact they could only shoot at night- to a series of funny customers episodes and even, well "romantic" story lines, the movie is based on a great script and works through the acting skills of its cast, especially Brian O'Halloran and Jeff Anderson.
In the end it's not just a great comedy, it actually manages to deliver something that can be called "a message", when, after main character Dante has survived possibly the worst day in his life, he has to admit that it wasn't all just bad luck but also a broad hint that he could/should change his life as a clerk.