Jeremy Heilman’s review published on Letterboxd :
The first twenty-minutes here, where Nolan lays out his structural blueprint, inspire awe, primarily because such bold declarations of cinematic ambition are uncommon. For much of the first hour, anticipation about what form this tripartite narrative will ultimately take takes the place of any need for deep characterization or even drama. Masses move across clean land, sea and airscapes setting something into motion, and the effect is mesmerizing, for a while. When the third act definitively reveals the gambit to be a typically well-ordered Nolan puzzle narrative, the impact of the human suffering on display is irrevocably deflated. Everything in this dazzling display of military efficiency is a pawn in a game. Perhaps nowhere is this made more apparent than during a scene in which a group of soldiers enact a real-time ethical trolley problem, in hopes of keeping a ship from sinking. This set piece recalls the brilliant prisoner’s dilemma sequence from The Dark Knight, but cast on top of real-life events the crude contrivance reveals the ultimately mechanical attitude that the filmmaker has toward these soldiers (even as it reflects military calculus itself). As a result, Dunkirk’s sentimental final movements, in which the word "home" becomes something of a mantra, fall surprisingly flat. Nolan reveals himself as The Joker.
Still, despite the director’s clear preoccupation with something other than humanity, Dunkirk also reveals Nolan as a great faker when it comes to depicting our kind. Numerous lump-in-your-throat moments of common decency and self-sacrifice are peppered throughout, doubly effective for being conveyed with great economy and a stiff upper lip. The performances, too, are varied yet accomplished, making more out of body language and proximity to the camera than dialogue (in late Nolan, what is being said matters less than the act of talking itself). Meanwhile, Zimmer’s score tick-ticks away, underscoring their ultimate, tragic lack of control in the scenario. The overall effect is a film that continually threatens to become overwhelming, both as an emotional experience and a virtuoso cinematic contraption, yet never quite convinces that it has much beyond Nolan’s own self-aggrandizement in its heart.