Ryan Lee’s review published on Letterboxd:
This screams from the beginning to be a tight action flick with little fat on its bones, but by the third flashback in the opening half hour, Leitch clearly had something else in mind. Thankfully, his desire to flash back to every stray mention, returning to every little moment once a payoff occurs—does he not trust his audience, or does he just think himself especially clever?—doesn't obfuscate Brad Pitt's star power in any way. Pitt gets a lot of exposition and empty quips in before this is over, but he's so effortlessly cool, smooth, and engaging to watch the whole time it doesn't matter. I'm not sure he saves the movie, though. It's not hard to follow, but there's a lot going on so that only so much gets its due, and that extends to the cast. Those whose characters get sufficient screen time (Pitt, a cool movie star; Henry, capable of so much range as ever yet in desperate need of a better agent; Taylor-Johnson, who gets to go crazy and then slowly dial that back as sympathy for him increases; King, who's capable but weaves in a strange meta element about her performance I'm not sure entirely gels) left memorable impressions, and everyone else either got in and out quickly, didn't contribute much, or appeared as a cameo (by my count, there's three: one makes excellent use of an actor's skill set, one saddles its actor with an accent for whatever reason, and one elicited a slight groan from yours truly). Still, they all seemed committed and like they had fun (sidenote: I await an American blockbuster that puts Hiroyuki Sanada to proper use), which reads as the point here—any thematic gestures about fate or luck or what have you are just kinda there. This was supposed to be fun...
...so why isn't the action better? I went in at least wanting Leitch to inventively use the train's geography in his action storytelling, and though a handful of scenes take advantage of the close quarters (Ladybug fighting the Wolf between two train cars, Ladybug and Lemon in the "quiet car" you've surely seen parts of from the trailers, Zazie Beetz's all-too-brief appearance), there's no attempt at wider clarity despite initial exposition that hints at it but never expands on it the way it should. On top of that, all the establishing shots of the train hurtling through Japan amount to nothing (I'd say the same for the Japanese flourishes as a whole, which really makes me want to read the source material for just how much was changed). But worst of all, though, is the third act: an ugly blur of digital fire, noise, and destruction, clearly showing the seams of a $90 million-ish budget and firing the remainder of its Chekhov's guns wildly. At one point, the film noticeably speeds up, as though Leitch wanted the film to end as much as I did...and then it went on for maybe fifteen or twenty minutes past that point. Ah well. Bullet Train is nonetheless fun in spurts and mostly entertaining, but it should be better and much more focused. Why haven't Suicide Squad’s cutesy introductory title cards been phased out yet?