From 2008, the documentary For the Love of Movies examines the evolution of film criticism. Interviews with critics of varying backgrounds describe their love of film and why they write about it.
Vachel Lindsay's book The Art of the Moving Picture (1915) is credited with being the first serious study of movies . As movies matured, film criticism followed suit. By the 60s and 70s critics were at the height of their influence on the culture. Their reviews could make or break a film. Some critics even went on to make their own movies, Peter Bogdanovich and Paul Schrader being two examples.
At The Village Voice Andrew Sarris popularized the French New Wave auteur theory, the idea that film directors are like the author of a novel. Pauline Kael's iconoclastic reviews for the The New Yorker revolutionized film criticism with incisive, deeply personal, stream of consciousness writing.
By the 1980s, a new crop of critics fueled by the video store revolution embraced mass media and film geekdom. Gene Siskel and Roger Ebert's weekly TV show turned the film critic into a something of a pop culture icon. Meanwhile a backlash arose against "elitist" critics who sneered at Hollywood's growing reliance on blockbusters. The rise of the internet leveled the playing field and gave rise to the cliche "everyone is a critic."
The documentary contends film criticism no longer matters. True to a certain extent, but the more voices the better. The good ones will stand out from the crowd. While podcasts and blogs have added so much to the conversation, it's increasingly difficult to make a living at it.
Print critics are still important as well. My favorites are Dana Stevens at Slate, A.O Scott at the New York Times, and David Thomson at Film Comment. All carry the torch of well informed critical writing.
Good criticism remains the same in whatever form it appears. For a history of the craft - check out For the Love of Movies (currently streaming on Netflix).