For starters this movie is slow-moving with very few characters so it's not an Underworld type in any way. You have this chick who is a vampire who befriends a young kid and then the story unfolds from there. There's not a lot of talking so most of the film uses body language and facial expressions to convey thought and emotion.
I'd have to say that the speed and music probably did it for me. It was a good combination that added to the overall ambiance of the film. Acting was good, especially from the up and coming actress Chloe Moretz (i.e. Hitgirl from Kickass). The guy was forgettable. So yeah if you're looking for a well-done vampire flick, look no further.
Rating - A