Sweeney todd was great and I loved that persona of Johnny Depp, it was dark and weird like edward scissorhands! But I guess I am a bit of a freak, I would guess that your 14-year old would not particularly fancy someone dressed in all black who kills people with a razor! or maybe not!
It is quite gory though, it depends on how sensitive she is. You do see all the blood flowing out when he cuts their heads off but it looks quite fake at the same time.