Buffy is a genuine cultural phenomena from the 90's. The teenager who constantly rids her small town of tons of evildoers – mostly nasty vampires (nevermind that she got involved with two of them) – served to inspire young girls to be more outspoken and brave and for boys to accept girls as their equal and worthy partners in life.
She also started the career of Joss Whedon – at the time an unknown and undeserving artist filled to the brim with ideas and today: the director of the largest blockbuster titles.
The series, alas, is an example of an obvious drop in quality. Its ideal ending comes at the end of the fifth season but the viewers wanted more. The sixth season saw a major drop in quality although there are still some good episodes there but the seventh season was a pain to watch – the whole time the protagonists are waiting for the big bad vampire to show up and nothing else happens. The finale … well, at least it ended things.
