It's a shame so many people have a negative knee-jerk reaction to movie musicals. I blame Paint Your Wagon.
Musicals have come a long way since the Freed Unit at MGM was pumping out a new one every 9 months. Not that I mind watching Gene Kelly tap dance his way around a studio backlot, but it has a certain amount of soggy, 1950s theatrical flair and pomp that rubs homophobes the wrong way. Their loss. The success of recent musicals like Chicago have reinvented the genre in what I think is a very positive way and injected it with new mainstream interest which is good; the subject matter in Sweeney Todd (serial killing barbers and cannibalism) is very different as far as musicals go but Burton's unique style is a perfect counterpoint for it.
The set design and costuming were very well done and exactly what you would expect from Burton - Gothic spires, dark cobblestone streets, lots of washed out tones and desaturated colors. There's very little light or color in the movie except for one memorable fantasy sequence and the blood which is bright, bright red for a little contrast.
The throat slitting is highly stylized, and the blood spurts out at 300 psi. It's pretty fantastic and much more tasteful than the sensationalistic blood letting of Kill Bill. There are only 5 or 6 principal acting parts, but the performances were very good all around (they've stolen half the cast of Harry Potter). Sacha Baron Cohen and the bulge in his tights make a memorable appearance as Mr. Todd's rival. The singing is pretty good (God bless you post production), and there is a lot of it, but dialogue and singing are interwoven together pretty smoothly. The closing tableau style scene, with the puddles of bright red blood and the fortissimo pounding of the orchestra was fan-fucking-tastic.
I applaud the studios for rolling the dice on this; musicals are a gamble, and a musical about a knife wielding barber who puts his victims into pies is even more so because you can't bank on the family demographic, and even though teens love gore they might not like it so much when it's being sung at them. In today's Hollywood, it's nice to see something different. Fortunately, Depp's star power and some creative financing kept it afloat and the result is a genuinely entertaining, highly different, macabre and stylishly produced musical like you probably haven't seen before.