Edgar Cochran’s review published on Letterboxd:
Having many things to say about this great film, I shall first provide an outline about my topics and then you can choose more easily where to focus:
I. Its place and importance in the Nūberu Bāgu movement
II. Commom complaints against the film
III. Basic recommendations on how to watch the film
IV. What makes this film very unique
V: Personal opinion of the film
Action fans: stay away. Girls and guys having a Gosha/Okamoto samurai marathon: leave this for another marathon. Shinoda is perhaps the most complex director to explore out of the Japanese New Wave. No film of his can be used as a reference for watching the next one in your watchlist; each delivery of his carries an undistinguishable signature from one another, from metaphysical representations of legends, to brutally honest condemnations of religious intolerance, to a yakuza crime thriller, to a brilliantly dramatic Shakesperian theatrical drama. He is one brilliant son of a gun.
Regarding Samurai Spy, he was against the conventionalisms of the samurai genre, even if the chanbara subgenre was emerging and treating moral topics adhered to the samurai code that began to explore even more complex moral themes and darker aspects of the wandering ronin and totalitarian authorities. Stepping away from the adventurous side of Kurosawa, he was aiming at a more realistic approach of the shinobi, and ironically, a fantastical touch to it when it comes to physics.
Remembering the contributions of the New Wave movement - you can think of the country that suits you the most as an example - Samurai Spy is literally what the title says: an espionage mystery film with no focus on action. So Shinoda's take was also to take advantage of the movement and apply it to the genre that you would think of the least: the samurai genre. The whole plot, then, functions as a noir, full of intrigues and double-crossings.
Given its complex web of characters and claimed difficulty to "follow the events" until viewers "lose all interest", the film provides, indeed, a difficult time for even experienced viewers to enjoy it, except for native Japanese viewers (heh). This complexity is even intensified with the opening historical context provided, where band sides are spelled out and the key conflict of the Battle of Sekigahara during the 17th Century is treated as the most important event unfolding the entire plot, a battle that allowed the Tokugawa to come to power in Edo. It later follows the antagonism between the Tokugawa and the Toyotomi in 1614, creating espionage parties on both sides.
If you have seen this film, you cannot say I am lying: you have difficulty memorizing names! It's too many Japanese name syllables to memorize in the opening 3 minutes, let alone the rest of the film! Simple. You may not agree, but it is simple. Have your DVD control by your side along with a pencil and a little notebook, and pause quickly every time a name is spelled out for you to remember and make a connection after the name is brought again. This is becomes so damn helpful, that you will even perfectly know who the guy that appears at the end is. It seems that the purpose Sasuke was seeking found him first!
"Jesus! Is this movie-watching time or a history class lesson? Is this school?!" Well, no; that's a very reasonable question. But hey, it will potentialize your enjoyment of the film! I certainly cannot make all character connections because I fail to memorize them if I do not write them down. If you were listening to names of your native country, you would have a sort of easier time following, and even so not that much. Suggestion sounds dumb, but it works a lot.
Final outcome? It took me 116 minutes to watch the 102-minute Criterion cut. That's 14 minutes of pausing. In my case, that's a very reasonable trade-off. Or are you willing to re-watch it and spend another 102 minutes? After your difficult initial experience, probably not.
As mentioned above (and I do want to make emphasis on this), the entire plot functions as a noir. With low emphasis on action like the more "standard" samurai film would have, a great cinematography, and splendid sequences of suspense, the film is ultimately a noir espionage film set in the 17th Century and featuring samurai and shinobi which intricacy follows the tradition of a complex Melville, such as Le Doulos (1962). Many New Wave directors had Hitchcock as an influence, and I might not be stretching this relation out too much if I said this film is included in that list. We are offered shadowy characters with undistinguishable intentions, people changing sides and revealing their true colors later, and the plot follows the structure of a mystery film with a sort-of-"who-was-the-killer" twist at the ending, putting so many pieces that had been unanswered beforehand. Props to the screenwriters for such effort!
However, it is imperative that action steps in; the genre demands it. When it does, against all earthly expectations, the characters are capable of pulling off stunts that might signal the very first baby steps of the wuxia genre, which complete foundations would be brought to Asian cinema by King Hu with Touch of Zen (1971). How is this supposed to be taken? Well, it should be taken simply as an artistic decision. That is why the final fight is more contemplative with its panoramic scope and more dreamlike with its constant use of fog, for stating an example.
With all things said and done, this is a damn unique film. It mixes genres as creatively as that famous western noir The Ox-Bow Incident (1943) that even featured moral lessons in between. It is unpredictable, with a very cool concept of a villain, a great camerawork, and even anime-like qualities in its treatment of dialogue handling and evil looks which you would only find in Japanimation many decades later.