This wasn't quite as bad as critics would have you think. The story's mystery is actually pretty good. The movie is dark and surprisingly violent, but it's funny when it needs to be. As you might expect, Gary Oldman rules your world, and mine too.
It has its fair share of bad stuff, though. The love triangle borders on obnoxious (hey, did you know it's directed by the director of Twilight?). Some of the "actors" are pretty bad...Amanda Seyfried is better seen and not heard, and the father is horrible.
Funny thing is, I can't recommend paying to see this, but I think you benefit by seeing it in a full theater.
I think the movie proved without Giles, Xander, Willow, Angel and a great supporting cast as well as great villains, Buffy is a one note character. I don't care what the cup size is of the new writer, its going to be terrible.