Today, these matters and manners may strike you as so very once-upon-a-time. Nobody "behaves" any more. In the post-Audrey age, when stars are in rehab before they're out of their teens, when British royals rut as strenuously as rock stars and a President gets impeached for accepting fellatio from an intern, deportment is a Victorian concept. Even in the 50s, a decade of such screen seraphs as Vivien Leigh, Claire Bloom, Grace Kelly and Jean Simmons (William Wyler's first choice for the role of Princess Ann), Hepburn was a glorious anachronism. She represented a moral and emotional aristocracy that no longer exists - if it ever did, outside of her pictures.
I'm not what you would call a devotee but I can see the appeal -- Hepburn's work is a testament to the elegance of a bygone era. (I'll admit I have not seen more than a few clips of her work, but I have seen her most contemporary-styled movie [and the one which marks the end of her days as a leading lady], "Wait Until Dark", and since I was a kid it's been one of my favorites).
I agree with Corliss -- Hepburn was elegant in a way that today's movie star couldn't even imitate, and times have certainly changed -- nobody really minds how the hottest young star behaves anymore. Their latest stint in rehab or DUI photo or off-the-cuff half-baked diatribe is catalogued in the tabloid press, but it's an amusing diversion not an offense to society. Even writing 'offense to society' is dorky today. Once upon a time we had Leading Ladies, now we just have movie stars. Is it the actors that changed or is it society that changed? It's a rhetorical question...both have changed.