Aliens arrived and tried to take over Earth. The humans beat them back, all-but destroying the surface in the process. Now decades later, a couple is assigned to look after the massive reactor plants producing the fuel required to power humanity's migration. The fuel plants need protecting because some of the aliens are still around and seem pretty bitter about losing.
Oblivion is a decent attempt at an action sci-fi blockbuster. It is entertaining in all the right ways and gorgeous to look at. The design work is fantastic from the cool house in the clouds that the couple live in to the blasted landscape of the ruined Earth, to whatever process they used on Tom Cruise to make him look 20 years younger. It all looks impeccable.
You may not want to read the rest of the review, so I will just up front say that Oblivion is a decent film if you like this sort of thing, with a few lapses that prevent it from becoming really great. Oblivion really isn't clever enough to avoid spoiling but if you really don't want to know anything stop reading now...
There were some things I really liked about Oblivion. The script has a some cunning little nods that hint that all is not what it seems right from the start. Starting a film with a lengthy voiceover describing the premise is trite but I liked the way the characters recite certain mantras later one including the voiceover word-for-word.
The general idea is not original, Oblivion is very similar to the earlier film Moon (which I liked) in a lot of ways (I wonder if Oblivion's shattered moon is a nod to the influence). But while Moon was a low key character study that gently let the audience discover the premise along with the characters, Oblivion is much more in-your-face, with lengthy action scenes inserted to liven up it. These look OK, but seem to have come from another film entirely or perhaps a video-game.
The acting is fine. Tom Cruise has dialed down his squintacting style. Morgan Freeman shows up as the world's last surviving black man. Nobody really stands out, but nobody really needs to.
As I said before, the script has some nice touches but there is some terrible dialog at the beginning of the film, and a silly speech at the climax that ruins some of the tone. There are also some pretty big plot holes (how did he build that house without either Vica or Sally knowing? What happened to the other clones presumably monitoring other parts of the Earth? Where did they get the other life pod?).
Oblivion falls into the gulf between a turn-off-your-brain action film and a thinking-persons sci-fi mind-bender, becoming a thinking-persons-turn-off-your-brain-action-bender, which doesn't quite work. Having said all that, Oblivion manages to be entertaining enough. Recommended if you like this sort of thing.