As several people have recommended, I saw the movie twice. Both times the theatre was fairly full, with varied demographics (from elderly people who had obviously seen the stage version to clueless teenagers.) Helena got precisely one laugh (of any kind) during both showings, and it was the same one--the post-Pirelli "Well, that's a different matter!" Not a sound during "Worst Pies", "By the Sea", "A Little Priest", or (what is arguably the most surefire laugh line in the show)--the post-"Epiphany" "Well, that's all very well, but what are we gonna do about him?"
There was also a palpable slump in energy during all of her songs at both showings, as one note after another wilted and fell into the chasms in between pitches. I noticed anew how static and claustrophobic most of the Sweeney/Lovett scenes and duets were (especially during "My Friends", which was also way under tempo.) An awful lot of Lovett slo-o-o-o-o-owly coming up behind Sweeney and putting her face next to his ear, as if the two of them were posing for stills for an Ingmar Bergman remake.
Other new questions---Why on earth did they keep "Wait" in its entirety? It's eminently cuttable--it would have been a kindness to Bonham Carter not to leave her vocal inadequacies so cruelly exposed for an entire lyrical solo. More to the point, why DIDN'T she cheer up Sweeney's tonsorial parlor as the money started coming in (with daisies, gillyflowers, or anything else?) If the barbershop had regained some of its former glory, the throat-slashings that take place there would have become both more horrifying and more domestic--we might have been shocked into laughter, instead of wondering why any sane Londoner would venture into that dark, dusty rat's nest for a shave.
Afterwards, there was a lot of "She really couldn't sing", "Well, she's the director's wife", etc., etc. And that's going to be the perception no matter how many times Sondheim insists he approved her casting. This movie had a chance to expand its appeal to people who don't go to movie musicals and who may never have heard of Stephen Sondheim. Because of Bonham Carter, I can't see that happening.
I ask in all honesty/What would life be?/Without a song and a dance, what are we?/So I say "Thank you for the music/For giving it to me."