How I felt about it. Perhaps the most anarchic of the Marx Brothers firms, although I still prefer A Night at the Opera at MGM. This Paramount picture benefits from the considerable screen time of Margaret Dumont, who remains ever oblivious to Groucho's insults and rejections of her counsel.
No harp solos or piano pounding in this short and wacky outing. Not much of Zeppo either, although he shows up in the large set scenes and even sings a little. There are two street vendor scenes that have nothing to do with the main story, and may have been added to pad the running time, and give more work to Chico and Harpo. The first street vendor skit is routine, however, the second skit is shorter and more successful.
One subplot only barely explored involves Spanish dancer Raquel Torres, an operative for scheming ambassador foil Calhern. She is to seduce Groucho, which will clear the field for Calhoun to court the wealthy Dumont. But Groucho and Torres only share a few lines, and for whatever reason, he has no interest.
The forgotten hero of Duck Soup is understated comic actor Calhoun, who shows uncharacteristic patience when dealing with his incompetent "spies" Chico and Harpo. His temper is much shorter with Groucho, since he is the obstacle denying access to the Dumont treasury.
The Marx Brothers are at their best when causing chaos. The larger the scale, the better. The ceremonies at the palace or legislature, with plentiful extras of dignified aristocrats or soldiers, are setting ripe for the mischief of Groucho and co. Singing, dancing, and silliness are ripe to follow. Groucho basks in his character of the most powerful man in Freedonia, but there's no danger that power will corrupt him. He's already completely cynical.
How others will see it. It's short, funny, fast-paced, and only the rare skit or scene seems extraneous. It's classic Marx Brothers, and only the ignoramus who avoids all old black and white movies will want to stay clear. For the rest of us, it's almost a laugh a minute.