One of the funniest Buffy episodes in my opinion, featuring some very funny dialogue such as:
Xander comenting on Dracula's castle, "You know, I've lived in Sunnydale my whole life and never noticed that castle next to the graveyard."
When Xander confronts Riley, he says, "If you want my master, you'll have to come through me." Riley responds with, "Okay", and lays him out with one punch.
When Giles goes to find Buffy in the castle, he falls into a room containing The Three Sisters. Riley eventually finds him and pulls him out. Giles notices his shoe is missing and says, "I seem to have lost my shoe. Silly me, I'll just pop down and get it.", but Riley stops him. Not exactly a funny line up hilarious in context.
Earlier in the episode Buffy slays Dracula, turning him to dust, but it was just a gypsy trick he learned during his existence. After the fight at the end of the episode, she slays Dracula again, and the dust settles. The camera follows the main cast as they leave the room, then pans back to where the dust of Dracula is reforming. The dust takes shape and from off camera Buff's arm stakes Dracula in the heart, and he becomes dust again. Beat. The dust on the floor and tries to recompile itself, but off camera Buffy says, "I'm right here!", the dust desides better on it, and lays motionless on the floor.
These are some of the examples of Joss Whedon's superb ability to write funny dialogue. And this episode was the entrance of Buffy's younger sister Dawn (a.k.a Scrappy Doo), though far from an identical twin.