The ad campaign is really weak for this one, in my opinion, as people not familiar with the original production wouldn't have a clue what they were in for. Which is, basically, a period slasher movie... that also happens to be a Stephen Sondheim musical. Almost more of an operetta, actually -- the spoken dialog is VERY limited.
I saw it this evening and thought it was fantastic. But, keep in mind that I'm the daughter of theater/musical theater/opera nuts and, while not a Sondheim fan in general, have loved this particular musical since I was a kid -- I fully knew what to expect. The family seated in front of us, however, was not terribly amused. It's very dark, and very musical-y (more true to the theater feel than others like Chicago and Moulin Rouge that have been at the center of the musical's mini-revival), but worth checking out if you're daring enough. Everyone sings well despite a lack of training, and the performances are very good across the board.