Although it was made nine years later, La Bamba is sort of a companion piece to The Buddy Holly Story, telling the story of the brief life and career of another of the musicians who died in that momentous plane crash in 1959 (the world is still waiting for the Big Bopper movie, apparently). Ritchie Valens was only 17, younger even than Holly, when he died, and he'd only released three singles, so he doesn't have the same kind of whirlwind musical career to focus on as Holly did (it's amazing how many classic songs Holly wrote and recorded in less than two years). Writer-director Luis Valdez instead focuses the movie on Valens' home life, and nearly half of it takes place before Valens has any success at all.
La Bamba is nearly as much about Valens' half-brother Bob (Esai Morales) as it is about Valens himself (played by Lou Diamond Phillips). While Valens is a straitlaced, ambitious kid, Bob is a screw-up and a drunk, who begins the movie having just been released from prison and proceeds to get himself into numerous scrapes, mistreat his pregnant girlfriend and eventually express resentment over Valens' success. Morales kind of overdoes the tortured-bad-boy routine at times, but the relationship gives Valens' story a depth that Holly's didn't have, showing the troubled background he had to overcome to pursue his dreams.
Valens' untimely death still means that there isn't much to his showbiz story, although Valdez, unlike The Buddy Holly Story director Steve Rash, shows the events leading right up to the deadly plane crash, and he plays up Valens' fear of flying and premonition that he would die on an airplane. That makes the coin toss that puts Valens on the plane especially tragic, which goes along with the way the movie emphasizes his volatile home life. It's less of a music story than a family melodrama, but La Bamba still makes a better case for itself narratively than The Buddy Holly Story managed.