I'd have let ds1 watch it at 13. I don't watch movies to vet them for him, because he mentioned watching several horror movies at a friend's house (kid was a total horror movie buff, apparently - how I didn't know that, after knowing him since he was 5, I don't know!). We talked a bit about them, and I realized that ds1 isn't bothered by a lot of the things that bother me. He processes it completely differently. (For example, I still can't watch the whole Aragog sequence in the second Harry Potter movie, and after watching LOTR: Return of the King about 50 times, I've never seen the entire Shelob scene. DS1 loves them both.)
When dd's that age, I think we'll have some major discussions about movies before she watches them. She's very sensitive in a way that ds1 isn't.