Claire Shaffer’s review published on Letterboxd:
For an industry based almost entirely in Los Angeles, filmmaking doesn't always portray LA in the most favorable light. If the City of Angels does show up on the silver screen, it's often for the purposes of being self-referential: fourth-wall jokes where the entire film is revealed to take place on a Hollywood backlot, producers yacking at their PAs for a latte exactly how they want it, actors cooped up in their trailers until they can get off the phone with their agents. Maybe a surfer dude or porn star will show up for some diversity!
Anyone who's spent at least a small amount of time in LA knows it's not all glamour and glitz. Most visitors' first reaction is amazement at how sprawling the place is; no, the beaches of Santa Monica are not a stroll away from the Walk of Fame. Welcome to your first LA traffic jam. And then there's the inevitable comment on the smog or how "dirty" the place is. What, and New York is clean? LA is a city, after all, and a working one at that. Even the beaches are crowded with muscular body-builders lifting more weights that I have in my entire existence. Angelinos are not so much "laid-back" as we are "taking advantage of every last drop of fucking sunshine we can get."
Chinatown was the first film I ever saw that got that. There were the classic film noir movies before it that understood the LA mentality as well, but their lack of color, stylized dialogue, and inevitable censorship didn't quite grasp the same charming-but-rough-around-the-edges mentality that J.J. Gittes embodies. Nicholson's and Dunaway's performances, Towne's script, and Polanski's directing together took the hard-boiled anti-heroism of noir characters and applied it to an entire city. The same man who abused his daughter robbed Owens Valley of her water, and the same man who sliced Gittes's nose depicted LA as the gorgeous wasteland that it is. As the famous final line of the film suggests, its inhabitants aren't so much interested in changing it as they are surviving it.
If you want to know just how this film subverts film noir and the classic image of Hollywood, just listen to the soundtrack - beautiful brass horns and piano mixed with unsettling dissonance and the sense that some blood is about to be shot out from underneath the gleam.