Noah Baumbach is quite the keen observer. When he renders a certain kind of person or place, he absolutely slays. His 40ish protagonists in “While We’re Young,” as well as the youthful hipsters to whom they fall prey,  are stunningly well drawn, cartoonish in their fidelity to their types yet completely realistic.

Like the intellectuals in his minor masterpiece, “The Squid and the Whale,” these characters are passionately literate about their interests. Baumbach sends up documentary filmmakers Ben Stiller and Naomi Watts a bit more fondly than he did the dastardly writer played by Jeff Daniels in “The Squid and the Whale.” But Baumbach, himself the son of New York writers and intellectuals, was channeling the kid (Jesse Eisenberg) in that one. There’s no better moment than Eisenberg, aping the father he reveres, tossing off the line “It’s lesser Fitzgerald” repeatedly.

(Photo/ Scott Rudin Productions) Ben Stiller and Naomi Watts are one of Noah Baumbach’s best screen couples.

(Photo/ Scott Rudin Productions) Ben Stiller and Naomi Watts are one of Noah Baumbach’s best screen couples.

However, the point of view in this film is firmly that of the Stiller and Watts couple, middle aged but just barely, to the extent that their best friends have a newborn and it’s only because of a series of earlier disappointments in that department that they dismiss the idea for themselves. They have turned a corner so recently that they can see clearly in both directions. Harkening them back toward their youth is the charismatic couple played by Adam Driver and Amanda Seyfried.

Driver attends one of Stiller’s continuing education classes and bowls him over with praise; soon the couples are going out to dinner, and Stiller is always picking up the check. Although she is more wary than her husband, even Watts falls under the spell of flattery and fun. While their old best friends, with their new baby, make them feel alienated, the new friends drag them along to hip-hop dance classes and street parties. If the entire film had nothing more to recommend it than Watts’ dancing, it would still be worth watching.

The funniest thing Stiller does is try to describe the documentary film he has been toiling away on for years. This film faces serious and soulful issues such as aging, and the longing for a child, while being funny throughout. A scene in which Stiller tries to pitch to a wealthy but clueless investor provides laugh-out-loud chuckles, but his desperation is very real.

The more the couples hang out together, the more Driver’s character casually takes advantage of them, particularly leveraging the fact that Watts is the daughter of a very famous documentary filmmaker, played by Charles Grodin. The film’s climax takes place at his Lifetime Achievement Award ceremony.

The climax is slightly underwhelming, but the set-up is so amusing and interesting. The young couple’s carefully curated retro objects, with walls full of VHS tapes and typewriters contrasts hilariously with the digital conveniences the older couple enjoys. These details support their claims of authenticity and devotion to pure process. However, as the film progresses, their actions begin to tell a different tale.

Ultimately all the filmmakers in the story clash over details about truth and intent in documentary filmmaking, and there probably have been more dramatic questions hashed out onscreen. However, the characters are the crux of the film and Ben Stiller and Naomi Watts are one of Noah Baumbach’s best screen couples. Marital happiness is not often found in his work, but theirs is a compelling, believable and satisfying journey.