A Taiwan/China/Hong Kong co-production, the film is loosely based on the late eighth-century martial arts story "Nie Yinniang" by Pei Xing.

The Assassin is loosely based on the late seventh-century martial arts story "Nie Yinniang" by Pei Xing, a core text in Chinese swordsmanship and wuxia fiction.

[7][8] The film is set in China during the Zhenyuan (貞元) reign period (785 to 805) in the middle of the Tang dynasty, a few years after the An Lushan rebellion (755 to 763).

The circuit of Weibo, though nominally a part of the Tang Empire, is de facto ruled independently by military governor Tian Ji'an.

The film centers on Nie Yinniang, an assassin who is directed to slay corrupt government officials by her master, Jiaxin, a nun who raised her from the age of ten.

The site's consensus states: "The Assassin's thrilling visuals mark a fresh highlight for director Hsiao-hsien Hou, even if its glacial pace may keep some viewers at arm's length.

"[25] On Film Business Asia, Derek Elley gave it nine out of ten, saying that "Hou Hsiao-hsien's first wuxia masterfully blends the genre's essence and his own style".

[26] Deborah Young of The Hollywood Reporter said: "Hou Hsiao-hsien brings a pure, idiosyncratic vision to the martial arts genre".

He states, "Mood is key here...[the film is] all muted and subsumed by a poetic atmosphere that's radical even by Hou's standards...It's a movie most will be intoxicated by, but few will be able to confidently say that they understand—which may be the point, part and parcel with its conception of a world of gestures and values so absolute as to be nearly unknowable.

"[28] John Esther of UR Chicago gave the film a more mixed review, saying "the real strength (and strain) of The Assassin is the mise-en-scène by Hou and director of photographer Mark Lee Ping Bing (In the Mood for Love; Renoir)" but was critical of the glossy depiction of the environment, "The costumes, the people, the woods, the art, and the interiors are relentlessly pretty.

"[29] Sarah Cronin of the British magazine Electric Sheep writes "The intricacies of the story are bewildering, with the 'who' and the 'why' only obliquely revealed as the film lingers on.

But rather than lending The Assassin an air of intrigue, these mysteries seem pointlessly and frustratingly obtuse, with the most potent symbolism left to be teased out of a broken piece of jade, while not enough is done to bring the characters to life, to make them whole.

Hou Hsiao-hsien deliberately avoids giving its audience any of the pleasures of wuxia, but its take on the genre offers little, and feels like a pale shadow of fellow auteur Wong Kar Wai's Ashes of Time.