Instead, and probably due largely to the involvement of DOP Claudio Miranda, it features breathtaking vistas of skies and sunsets, all achingly gorgeous because they've been projected onto gigantic screens that encircle the set. Most of the time there's no green screen, and the actors can, well, act, as if there were actually there, in the scene.
Another advantage of the projection technique technique is that the light illuminates the set and the actors, which simply makes the whole thing look more real. This is virtually impossible with green screen techniques. What's more, it completely alleviates another common keying problem which is that the colour from the green screens can be reflected on white or clear surfaces and has to be removed in post - making what is already a laborious job even harder.
And it's immediately obvious that the technique works. The film's had mixed reviews (although mostly positive) but whatever conclusion you come to about the plot, you're not likely to be disappointed with the visual experience.
Here's an extended look at the making of Oblivion: