I'm not a fan of Sondheim.
There, I said it. He's very overrated as a composer and songwriter.
SWEENEY TODD is a very strange musical. It's a black comedy that's not very funny, and without a single memorable song. The best part of the musical is the book, which is usually the least important aspect of a musical.
The weakest part of the book is the first act, and that stands true in the movie. Tim Burton does his best to rise above the difficult material, with the excellent casting of Johnny Depp, Helena Bonham Carter, Alan Rickman, and Sacha Baron Cohen, but the first third of the movie slogs along endlessly until the murders finally begin. Yet there is also the bizarre casting of several unknowns who are very weak, including eye candy Jayne Wisener and Ed Sanders.
The visual design is excellent, as always for a Burton film.
It's worth seeing, but certainly not awards-worthy.