Some of Wilder's officially-sanctioned masterpieces don't hold up that well for me: Some Like It Hot just doesn't seem all that funny to me any more, with its rambling storyline and some surprisingly lame comedy lines. But One, Two, Three just keeps looking better and better: a movie so timely that an opening narration had to be added to cover events that happened after it was filmed (at the time of filming, there was no wall between East and West Berlin; the border was sealed off just after the movie wrapped), it holds up because it's a perfect distillation of the culture and concerns of the early '60s. Two continents' worth of politics, pop-culture, marriage and business are contained and dissected within one movie.
It's also a catalogue of pop-culture references. Wilder was one of the first filmmakers to load his movies with references to older pop culture, as witness the many movie references in Sunset Blvd. and Some Like It Hot. One, Two, Three has all kinds of references to pop culture of the time, and to older stuff, including the work of star James Cagney: in one scene, he imitates the grapefruit routine from The Public Enemy, and Red Buttons (in a cameo) does an impression of Cagney's Angels With Dirty Faces shoulder-hitch.
The movie is carried almost entirely by Cagney, of course, though Pamela Tiffin (one of my favorites of the "Lost Starlets of the '60s") does a fantastic job with a character who shouldn't have been interesting at all. Wilder, never generous to his female characters, has nothing but contempt for Tiffin's southern-belle-ditz character, but Tiffin manages to convey the impression that her character isn't so much stupid as deeply weird. (Luanne on "King of the Hill" is a somewhat similar character.) Her line readings make Scarlett into a more sympathetic and likable character than Wilder probably intended her to be.
And anyone who's seen the movie can quote a lot of lines that are hilarious in context and not so much out of context:
"In the old days, when I ordered them to sit, they would sit. Now it is a democracy, they do what they want, and what they want is to stand."
"Call Dean Rusk, Dean Acheson, Dean anybody."
"Das is kuckucksur."
"We will give you Chinese cigarettes! Armenian rugs! Bulgarian yogurt?"
"Two out of three! Deal is on!"
"I will have you know that I am distantly related to Ex-King Farouk of Egypt."
And most memorably, the use of two songs: "Yes, We Have No Bananas," and "Itsy-Bitsy-Teeny-Weenie Yellow Polka Dot Bikini." I will not give away what Wilder does with those two songs, but suffice it to say, those are the two moments everybody seems to remember most.