This is a hard movie to review without diving much too deeply into social and political issues that for the most part aren't mine to comment on. Even in the barest summary, alarm bells start ringing: medieval European travelers to China arrive at a critical point in a cyclic invasion of ravening monster hordes to help win a decisive victory. And all the gorgeous visuals, the prominent female lead (who is--miracle of miracles--not a romantic interest), the big name Chinese director (Yimou Zhang), and the creative presentation of a multi-lingual story cannot entirely redeem the movie from being a White Savior vehicle for a Hollywood star. All that cannot erase the knowledge that a nearly-identical movie that didn't ease white western movie-goers' insecurities by centering Matt Damon's character in the plot would have struggled to escape art house theaters in the US market (as, for example, the director's previous works Raise the Red Lantern and House of Flying Daggers, to cite titles I recognize in his IMDB listing).
It isn't that the movie (and especially this choice of director) didn't try its best to rise above the White Saviour/ travelogue tropes--and succeeded far better than one might have expected--only that escaping them was impossible, given the underlying story. Even the standard trope of "supposedly civilized European is revealed as filthy barbarian in contrast to sophisticated Asian culture" can't escape centering the western gaze, if only because the movie instructs us to identify with Damon's character, and because his critical contributions to the victory carry the message, "What this advanced civilization needs is a virile barbarian."
And yet...and yet...this is a stunningly beautiful movie. For a "fight the unending monster horde" plot, the events hold together and have a solid underlying logic (if a questionable ecological dynamic) that makes the eventual resolution both earned and rational. It gets massive props from me for not inserting a romance between Damon's character and Commander Lin (Tian Jing) in a setting where the default Hollywood plot would require one. The Chinese characters in the file were cast with Chinese actors or actors of Chinese heritage (as best I can tell), and as a linguist I loved the handling of spoken/subtitled language. I enjoyed this movie as entertainment, but in doing so I recognize that there are a lot of currents flowing through it about representation and Hollywood power dynamics that I am not a right person to evaluate.