As in Hoffmann, the film is full of dancing--but much of it has an improvised flavor, a polka down the hall, a can-can by Michael Redgrave in full military evening dress and kepi, as well as lots of waltzing-- and some of the actors are lip-synching the arias as sung by folks with bigger voices. But there is also a lot of spoken dialogue, so the actors get to establish their characters in their own voices. The trouble is that the characters are still the silly, exaggerated characters of an operetta, with chiming watches, comic hangovers, and huge plot-enhancing blind spots.
The most interesting character is of course Anton Walbrook's Dr. Falke, the Bat. As in The Red Shoes and La Ronde, Walbrook plays the man who keeps the whole thing going, the leader of the dance, but here he is euphoric, almost ecstatic. Falke is presented as a black-marketer who arranges parties for the higher-ups of the Four Powers occupying Vienna, and keeps them on good terms with each other; he exploits them, lives off them--and he would like to see them all go home. He is witty and views everything with cheerful irony, but he never stops enjoying himself for a moment, never goes down, only up, up, up.
Ludmilla Tcherina is a delightful French farce heroine, flirting only when absolutely necessary. Michael Redgrave gets to do some great swooping physical comedy (apparently he also did his own singing, but who can tell?). Mel Ferrer comes off well in his light role as the old boyfriend, as does Dennis Price in a smaller role whose main duty is to be recognizable for plot purposes. Anneliese Rothenberger is a reminder of more conventional stagings, where the singers act instead of having actors "sing."
I felt that the 1955 setting was a bit thin--were the 50's really THAT much about denying what had happened and "moving on"? Maybe they were--Pressburger and Powell were good at telling where the wind was blowing.