What's the difference between a derivative knock-off and a clever or loving homage?

Like beauty, it seems to be found in the eye of the beholder. Critics loved 2011's "Super 8," J.J. Abrams' rough tribute to Steven Spielberg that felt exactly like a Steven Spielberg film. But so far, they're rather less enamored of "Oblivion," Joseph Kosinski's tribute to 1970s and '80s science-fiction films. It's puzzling, because though its allusions are plenty and sometimes plenty obvious, "Oblivion" is a more original piece of work than "Super 8." It's also more entertaining and much more beautiful.

The year is 2077, and Earth has been through, as we've seen on screen many times before, an apocalypse. This one was brought on about half a century ago by alien invaders. "We did what we had to do. Used the nukes. We won the war. But lost the planet," Jack (Tom Cruise) explains to us in the movie's longish narrative opening. Every human being has been shipped off, for safety, to Titan, Saturn's largest moon. Everyone, that is, except the people sent to do a stint of clean-up on Earth.

Jack and Victoria (Andrea Riseborough) are two. They make up a team that looks more like a married couple -- Jack and the very sexy Victoria share a bed as well as a mission. Victoria stays at the space station that's home base, while Jack ventures down to Earth's surface every day to maintain the drones that have been left to kill off the rest of the alien invaders, called scavs (presumably, short for "scavengers").

On screen
» Rating: 3 out of 4 stars
» Starring: Tom Cruise, Olga Kurylenko, Andrea Riseborough, Morgan Freeman
» Director: Joseph Kosinski
» Rated: PG-13 for sci-fi action violence, brief strong language and some sensuality/nudity
» Running time: 126 minutes

Victoria is pleased that the two have almost finished their duty and will soon be shipped back to Titan -- though a memory wipe means they don't know what life is like there. Jack is more unsettled. He still feels a connection to Earth: It helps that he's found one small part of it that's still beautiful and keeps a secret house there, filled with trinkets from the time when humans still filled the planet. He also can't shake the feeling that he actually lived in the prewar Earth. An image recurs in his mind of the top of the Empire State Building and a beautiful woman there. "I know I'm dreaming, but it feels like more than that. It feels like a memory. How is that possible?"

When he finally meets the woman of his dreams, his whole world is shattered. Julia (Olga Kurylenko) is the sole survivor of a NASA spacecraft that lands on Earth -- because Jack saves her life. The drones kill every other crew member. But Julia won't tell Jack where she's come from or where she was going, and Victoria doesn't like the looks Jack and Julia give each other. ...

For those who have watched a lot of science-fiction films, the mystery at the heart of "Oblivion" might not be terribly difficult to solve. But it's not the point. "Oblivion" is a love letter both to the futuristic films of the '70s and '80s and the Earth-bound pop culture of those times. Why does Jack have a collection of LPs at his secret house rather than CDs? Because they're more beautiful, one imagines. And Led Zeppelin and Procol Harum do sound awfully good on vinyl.

The story here can veer into the preposterous at times, as stories of this sort often do. But more important, it provides Tom Cruise lots of opportunities to look cool. The 50-year-old actor still has it. (Though the film can't help reminding us of the younger Cruise: One of the items in the house is a pair of "Top Gun" sunglasses.) The English actress Andrea Riseborough is exceedingly elegant, but Olga Kurylenko and Nikolaj Coster-Waldau, as a member of the human resistance, aren't given much to do.

The early critical reaction to "Oblivion" shouldn't keep you from seeing a film more thoughtful than its big special effects would suggest it is. Critics might think this film takes too much from its predecessors in the genre. But how many big-ticket movies have a poem by Lord Macaulay at their center?