Maybe it doesn't quite live up to the genius of its reputation, but there are a number of brilliant comic moments. That said, the film itself is uneven - there are far too many musical numbers, and it sometimes gets bogged down in subplots involving supporting characters. Uneven, but still a supremely entertaining classic.
The conventional story slows it down, but there are great moments when the brothers get loose, like the breakfast with the police arrival. Funny that it's so next in time with Disney's The Band Concert and both have classical music "sabotaged" by popular tunes in a gag.
Duck Soup is the Marx Brothers at their creative and madcap height, but A Night at the Opera is them at their tender and lyrical height. Plus innumerable hilarious bits: sanity clause, two boiled eggs, four beds, more, more. Harpo's harp scene is one of the most magical moments in film.
It may be just under Duck Soup as the Brothers' best, but this classic is by far their most accessible. With a romantic subplot, plenty of songs, and the Brothers on a mission to mayhem & helping the budding romance, the film is a delight even if you'd prefer the songs to be skipped. If the jokes on war might go over the heads of some on Duck Soup, the jabs at the seriousness of opera is an easier target!
Overall, weak. Lets face it, Marx Brothers films are a series of sketches and gags tied together by mostly poor stories with some songs thrown in here and there. I totally respect that due to their vaudeville performance styles, but with this film, the gags just fall flat. Both collectively and singularly these skits are far too over the top and are totally lacking in wit and class.