This is a stylish but staid addition to the growing subgenre of action films featuring elaborate, cartoonish criminal underworlds. A crude assumption about Gunpowder Milkshake might be that it simply wants to be the "girl" version of John Wick. And the film does seem to base a lot of its comic book-style world-building on the rules established in the Wick films, such as creating a crime community with tons of eye candy, like a 1950s-style diner; a retro, slick hospital that exists outside the bounds of mainstream healthcare; and a library where guns are available for checkout. How do these structures exist without being raided by the police? Gunpowder Milkshake doesn't answer that question. (Neither does John Wick, for that matter.) But while the John Wick franchise does try to explain some of how its world works, Gunpowder Milkshake isn't interested in having those conversations. Instead, it relies on viewers' prior familiarity with John Wick to fill in the gaps of how an implausible world of assassins can exist. That works against the film, since it prevents it from becoming its own entity.
Despite its star-studded cast -- including heavyweights like Bassett, Yeoh, Gugino, Headey, and Giamatti -- the film's focus is more on style than substance. Circling back to the John Wick comparison, that franchise is also full of glitz and glamour amid the killing sprees, but the films boast more threads of pathos than Gunpowder Milkshake. Case in point: Emily, the girl that Sam is protecting, doesn't mourn her father's death long enough for the audience to internalize her pain and loss. Instead, she either doesn't have enough time to mourn due to the action, or her emotional state wasn't deemed important enough in the script. And her later rationalization about the circumstances leading to her father's death also feels too convenient for the plot. That said, Coleman does a good job at making such lines sound convincing. Meanwhile, Yeoh, Gugino, and Bassett turn in performances that range from passable (Yeoh, Gugino) to clunky (Bassett, alas). Perhaps it's a case of the actors not having enough characterization to latch onto, because we know they can act. As Sam, Gillan isn't charismatic enough to find the fun in her character. Her wooden performance makes it hard to stay interested in Sam's journey from villain to anti-hero. Ultimately, the most convincing actor is Giamatti, who always seems able to turn in compelling performances even in the wackiest of films. With fewer scenes than any of the major characters, his character, Nathan, is the only one who truly grounds viewers in this zany world of libraries full of guns, assassin diners, and mysterious criminal firms. Overall, Gunpowder Milkshake seems more interested in being flashy than in entertaining its audience.