I saw this movie just a couple of weeks ago and I absolutely loved it. Johnny Depp and Helena Bonham Carter were both perfect for their roles- I couldn't imagine anyone else playing those parts better than they did. He was as brooding and intraverted as she was vivacious and demanding, and he's so absorbed in his obsession with revenge that he never notices her affections. I never saw the on-stage version, so I don't know how it compares, but the movie is a very de-Broadwayized version, with no big dance numbers or anything, and the singing is more about expressing the characters' thoughts and feelings than showing off the actors' voices. (All of the leads have surprisingly good voices for never having sung before, though.) There is a lot of blood, but it looks kind of like red paint, and I didn't find it too bad.
...oh, and the costumes were wonderful- I wanted to steal just about all of their clothes.
Anyway, that's me gushing about Sweeney Todd. If anyone else, er, wants to say something, they... can. Yeah.