I'm not sure what to make of this film; is it a sci-fi alien invasion film, a mystery, or a romance? It tries to be all three at once, although I'm afraid it doesn't quite succeed. Instead of melding together to form a coherent whole, these disparate styles cause a chop-and-change effect, which interrupts the flow of the film.
Set in the year 2077, Earth has been attacked by an alien race called Scavengers (Scavs for short). Even though humanity won the war, it was a hollow victory: the means employed to defeat the invaders has turned large areas of Earth into an irradiated wasteland (we're talking nuke war, people). Because of this, man has abandoned its ancestral home, relocating to titan (the largest of Saturn's moons), leaving a skeleton staff behind to assist in the stripping of Earth's resources, for use in the new colony. Jack (Tom Cruise) is a futuristic repair man, working hard to keep a fleet of combat drones active and protecting the resource collecting machines (the Scavs still occupy Earth, and continually attempt to sabotage the human's efforts to survive). Victoria (Andrea Riseborough) is his stickler-for-the-rules air traffic controller, trying to keep him focused on the final two weeks of their mission. The problem is that Jack is plagued by memories from a life lived prior to the invasion, which should not be happening, given that both he and Victoria's memories prior to their mission have been wiped, in case they should ever be captured by the enemy. The other issue is that Jack displays a degree of curiosity for the past, and likes to collect pre-war knick-knacks, behaviour which would be frowned upon by Sally (Melissa Leo), their contact from mission control, housed in a space station orbiting Earth, but only if she finds out!
The plot takes a turn when a human craft is brought down by the Scavs, and the survivors are attacked by the combat drones, with only one spared, and that only because of the intercession of Jack. Julia (Olga Kurylenko) is the survivor, and her coming heralds a shift in the relationship between Jack and Victoria, and even Jack's desire to complete his mission.
Also of note is Morgan Freeman as Beech, leader of a rag tag band of humans who have remained behind on Earth, for reasons which become clear as the film progresses.
Although there are many visually beautiful moments in the film, and several homages to sci-fi classics of old (the red eye of the combat drones harks back to the psychotic computer HAL from 2001, whilst their shape reminded me of the small robots in Disney's The Black Hole) Oblivion ultimately suffers due to its languid pace (intended, no doubt, to generate suspense as the plot twists are slowly revealed, though instead creating a generally soporific effect), and from the awkward gear shifts between the different aspects of the story line.
In the end, I was looking forward to the film ending, after the anti-climactic final scenes.