When “Elysium” opens on a dirty, overpopulated Los Angeles circa 2154, it looks a whole lot like the dirty slums of Johannesburg in “District 9,” director Neill Blomkamp’s previous film. But that’s not the only similarity. The films share progressive social commentary, distractingly bloody violence and the comforting presence of actor Sharlto Copley.

But, while “District 9” was an intimate film with some grand ideas made on a relatively small budget, “Elysium” is about as ambitious as they come. Blomkamp has a larger budget, A-list actors and an obvious commentary on the 99 percent. While larger in scope, the film gets lost between its idealism and its desire to be a crowd-pleasing popcorn movie.

The aforementioned slum known as L.A. is occupied by ex-convict Max (Matt Damon), who is trying to live his life straight while working as a mechanic for a robotics company. He and the rest of the world’s poor live on Earth, while the privileged have abandoned the planet for Elysium, a spherical structure filled with immaculate lawns and machines that can instantly cure all diseases and ailments.

Elysium is run by the menacing Secretary Delacourt (an icy Jodie Foster), who makes it her mission to assure any outsiders are immediately detained or killed. And, with desperate residents of Earth looking to cure their diseases, that happens pretty often.

But after a work accident leaves him with radiation poisoning, Max is determined to make his way to Elysium to be cured. Once there, he may have a chance to liberate Elysium and bring quality healthcare to the rest of the world.

“Elysium” sets its overtly political conflict (99ers vs. 1 percenters, healthcare reform) front and center, before diving straight in to an intense chase film, with Max being pursued by Delacour, who hires a bounty hunter named Kruger (played with positively medieval menace by Sharlto Copley) to hunt him down. The film moves so quickly it almost feels rushed; much of Max’s character development comes through a repetitive and obvious framing device involving flashbacks to his childhood. Kruger and Delacour, despite excellent performances from Foster and Copley, never come off as much more than manufactured menace.

Trent Opaloch’s gritty cinematography helps to sell the film’s version of Earth not as speculative science fiction, but as an almost-inevitable look at our planet 150 years from now. The film’s violent action scenes recall the best moments of “District 9,” especially in its handheld camera shots that lend the film a faux-documentary aesthetic. Unfortunately, these scenes also feature distracting slow motion, an overused trope that is always a sign of a filmmaker’s more grand, crowd-pleasing tendencies. By the end, the numbing action overrides most of Blomkamp’s on-the-nose political commentary.

As a writer, Blomkamp brings something unique to the table beyond his politics. Raised in Johannesburg, South Africa and now living in Vancouver, the filmmaker has never considered himself an “American.” You can almost feel his glee as he turns L.A., a city that, in our world, can sometimes look more like Elysium, into the crowded, multicultural Johannesburg slum he knows so well. In the film, you’ll hear English, Spanish, French and German spoken. Much like “The Wolverine,” it’s the rare action film with a true international focus beyond exotic locales.

While the film looks great, I would have loved to have seen more of Elysium itself. While everyone on Earth seems to want to go there, all Elysians seem to do is lounge in pools and eat exotic desserts. But, when Max and crew arrive, we’re left to looking mostly at dark corridors.

Thank God for Matt Damon. He effectively sells Max as a sympathetic everyman. He’s one of a select few who can look convincing running and gunning or sobbing quietly in pain. And man, that guy can take a beating. It’s easy to get used to him because he’s in so many movies, but he consistently reminds why he is one of the best actors in the business.

“Elysium” is one heck of a ride. But, unlike “District 9,” it doesn’t sear in the memory. In its best moments, it recalls the magnificence of Blomkamp’s previous effort. In its worst, it’s almost laughably silly. That doesn’t stop it from being a tense, sometimes brainy roller-coaster.

“Elysium” is living proof that it’s better for a film to shoot for the stars and come up a bit short than to never even try. And, in a summer movie season of playing it safe, such ambition is worth celebrating.