Though I had high expectations for this movie for being much spoiled of how great it is, I was still pleasantly surprised by Detective Chinatown 1900. As a Chinese immigrant, I'm proud that it's a mainland Chinese director who decided to touch upon topics of immigrant laborers, the Yellow Peril, and the Chinese Exclusionary Act, and further at how well this part of history is adopted, recreated, and incorporated with the overall storyline of the movie --- as it goes, Chen Sicheng is a true merchant in terms of selecting film subjects. Chow Yun-Fat gives hell of a performance for a multilayered Chinese-American hero: a loving father, an approachable elder, a cunning diplomat, and an authoritative (mob) leader. Bai's speech at the court is a rare scene of cultural outcry that struck me personally and inspired new reflections.
Notice how I never mentioned the "detective" bit of the movie? The crime/investigation storyline is decent but not amazing compared to the rest of the franchise, complexity and portrayal wise. Some parts of the murder even took me out in terms of the absurdity and logistics, which leads me to question if the director has a thing with pregnant women (cue his last film Lost in the Stars).
Overall, enjoyable comedy, ambitious multi-storylines, and great performances across the board. Keep in mind, however, that this film is targeted toward the Chinese market/audiences and it's meant to educate, provoke, and moralize, perhaps in a way you might not agree with.