The scene when the elevator door opens and..... (spoilers?)
then you see Christine wearing a bloody scarf, a pair of sunglasses, and dressed in black was so awesomely made, I don't know if it was De Palma, or Mcadams, or the background music (reused from another De Palma's film but it was good) but those were the most effective 5 seconds of the entire movie. really really really really.....really........like...... really spooky.
I replayed that scene for over 20 times. I liked it.