Sweeney Todd: the Demon Barber of Fleet Street (18)

This comic-gothic rendering of the Stephen Sondheim stage musical has so much potential that you could weep for the way Tim Burton squanders it. As a Sondheim fan I looked forward to this, and even the rather predictable casting of Johnny Depp and Helena Bonham Carter didn't seem too bothersome. Depp, channelling previous oddball roles, notably Edward Scissorhands, plays the demon barber as a whey-faced revenant, with a streaked hairdo that's somewhere between the Bride of Frankenstein and Susan Sontag.

Back in London 15 years after being unjustly deported by the corrupt Judge Turpin (Alan Rickman), the barber finds his wife dead and his daughter the Judge's ward and prisoner. Driven by psychotic rage, he cuts the throats of his customers and tips them into the basement, where his landlady Mrs Lovett (Bonham Carter) uses the corpses as filling for her meat pies.

Sondheim's droll lyrics and lush harmonies finesse all this into a compellingly macabre comedy. Even when the singing is no more than passable (Depp does a cockney croon that nods to David Bowie), the tunes come up trumps – "Pirelli's Miracle Elixir", "Worst Pies in London" and "Pretty Women" are terrific.

But it looks awful. Dante Ferretti's sets aim at a fantasia on mid-Victorian London but are merely drab, ugly and claustrophobic, the only concession to colour being the bright red blood that spatters the lens in the final third. Burton wants to style it as a black-hearted fairy tale, but his camera movements feel sluggish and one keeps sensing a gulf between his idea of the musical and his execution.

Neither Depp nor Rickman provides real menace, and the romantic subplot of Todd's young friend Anthony (Jamie Campbell Bower) and the imprisoned Johanna (Jayne Wisener) is hopelessly wet. It's reminiscent of Francis Ford Coppola's Dracula in the way it plays with horror without ever conjuring the real thing. I hope it doesn't deter film-makers from doing Sondheim – a genius, after all – but this take on his "Todd" is not a great advertisement for his work.