Re: Oh wait I've seen two of those.
Buffy doesn't take that long to get good. The first season is mediocre, but it's only twelve episodes and you could easily skip all of them except the two-part pilot, "Angel", and the finale. Or you could just skip it all and start at Season 2, which most fans would agree is the best of the series along with Season 3. If you don't enjoy season 2, you are highly unlikely to like the rest of the series.