The French Connection
For a movie billed as containing the most exciting car chase scene of all time, this was a considerable disappointment. It's not hard to spot the influences and see what the film was trying to do: it's an attempt at a French gangster heist noir in the style of Jean-Pierre Melville, except focusing on the police rather than the gangsters; it's like nothing more than a bizarro-adaptation of Le Samourai. Thus Melville's characteristic objective camera presence, establishing little about the plot and less about the motivation of the characters. It doesn't hold up to the Melville example because the stakes of the average Melville film are personal even when placed in the midst of objectively difficult situations: each individual person in Army of Shadows, Le Samourai, or Leon Morin, Priest are attempting to stay alive and maintain their personal integrity, regardless of whether they are working with the Free French or possibly selling them out, working as a hitman for mobsters, or attempting to win converts. One may know little or less of the details of their social situation because those details are irrelevant.
The French Connection relies too much on its setting to give significance to the actions of its characters: one needs a sense of a New York City crumbling into total decay, of police overwhelmed in their attempts to do good, of heroin as a scourge that will make things even worse.* One could even accept setting up the plot as a reverse-Casablanca, where the intense effort put into stopping this shipment is a losing cause because it is only one small problem amongst many of them. As it is, the audience is given little reason to care about the actions and fate of these two detectives, and no sense of where this fits within the overall scheme of a situation left unexplained. I would not be surprised to find out that this film's critical reputation is strongly correlated to how close to its premiere one first saw it.
*Those of us watching it now have the benefit of hindsight to know that none of these will end up being particularly true, which undercuts its realism.