[1] Both women encounter entrepreneurs and government authorities seeking to promote a sanitized version of the language and to commercialize it to brand products including "high-end potatoes".

[7] Dennis Harvey, writing for Variety, said the film offers "a meditative, finally upbeat pulse-taking of a sisterhood," with "a gently questioning perspective on whether the issues this now-quaint private language addressed retain currency in today's China, where economically driven progressive attitudes may as yet only superficially impact deep-seated cultural ones".

[2] Patricia Aufderheide wrote for Documentary.org: "Feng and Qing give us an uncommented but highly pointed close-up look at the contradictory meanings of Nushu today, from the perspective of the women they follow.

[8] Damon Wise wrote for Deadline that "Unlike the majority of docs, Hidden Letters doesn’t really set itself a goal—it's more of a mosaic piece that, in its best moments, has the vérité feel of a late-'60s Maysles brothers movie".

[1] Devika Girish gave the film a negative review in The New York Times, writing that its "attempts to connect the past and the present feel too glib, lacking the force of historical detail.