I have to say, I really wish that the show had taken the opportunity to truly update the look. Keep the same themes but make it not so super-heroiney. Almost like "Smallville," where Clark was always wearing red and blue but not a costume. (Of course that's a different situation, because Clark hadn't embraced the Superman persona yet, but still.)
I'm probably just biased because I love Buffy so much. I liked how she was basically a superheroine hiding in plain sight. That's my kind of superhero. I've never been big on the overtly costumed type.