Why some people criticize this as "the cheesiest, corniest movie ever"
This was one of two films Francis Ford Coppola shot back-to-back based on S.E. Hinton's young-adult novels. "The Outsiders" was successful at the box office while the even more artsy "Rumble Fish" (1983) failed to draw an audience.
Hinton began writing "The Outsider," her most popular novel, in 1965 when she was 16, inspired by two rival gangs at her school, Will Rogers High School, which is about 2.5 miles west of downtown Tulsa. I bring this up because the movie definitely comes across as a melodramatic tale from the perspective of a teenager.
The most mundane, trivial events are presented as life-or-death happenings, like going to a drive-in theater or facing your nemeses at a park where one person idiotically brings a switchblade to a fistfight.
This explains why some people write the flick off as "the cheesiest and corniest movie ever." In its defense, you have to acclimate to it in order to appreciate it. Go back to what was happening in your life when you were in your mid-teens and how a fistfight or breakup was an earthshattering event. The movie captures this very well.