Richard Heuberger's 'Der Opernball' is not quite one of the greatest operettas like 'Die Fledermaus' and 'Die Lustige Witwe', containing a corny and old-fashioned story where one really has to suspend disbelief in places.
However, it has a lot of enjoyment and charm, with comedy that genuinely entertains, has charming characters and while there are slightly more memorable operetta scores the music is beautiful and tuneful, the most famous being "Im Chambre Séparée" (colloquial for "Komm Mit Mir Ins Chambre Séparée".
This 1939 film of 'Opernball' is a good one, and does a good job maintaining the fun and charm. The comedy really does sparkle, and the storytelling is elaborate and snappily paced with plenty of parts to make one laugh and go ah. It does start off a little slow and it doesn't do enough to make a couple of the antics less corny or suspension of disbelief is very much needed for when the women are disguised.
'Opernball' is beautifully filmed in black and white, with lavish costumes and sets, while the music is still beautiful and tuneful and performed with liveliness and attractive tone. It's solidly directed too, and boasts fun performances from the whole cast, with nobody quite outstanding (though Hans Moser definitely steals scenes) but nobody's awful by any stretch of the imagination.
In conclusion, enjoyable and charming. Worth tracking down. 7/10 Bethany Cox