I don't normally enjoy musicals. Neither am I particularly fond of slasher films. However, Tim Burton's blend of the two is surprisingly enjoyable. With an engaging story, effective use of comic relief, and just the right amount of Pythonesque exaggeration added to the throat-cutting scenes to make the blood tolerable, Sweeney Todd was a very pleasant surprise.
I think part of what sets this story apart from most films about deranged serial killers is that it focuses on the plight of killer rather than that of the victim. Instead of having a film in which a victim is chased around by a mysterious villain, or a detective is tracking down said mysterious victim, we see predator struggling to lure his primary target into a situation where he can finally get his revenge. When he finally does so, the play ends it a near-apocalypse much like Hamlet does.
The movie is typical of Tim Burton's work in that it is a bit strange and quite dark. As such, it is difficult to label it according to any typical dramatic definitions. It is not comedy, tragedy, romance, and certainly not epic, but it is very entertaining. I would recommend to anyone old enough to handle the mature thematic elements of the story.