It sounds like it isn't much of a movie, based solely on this synopsis. But it actually is a pretty remarkable film. It looks fantastic. It might even give you a little bit of vertigo and it clearly isn't intended to be a recruiting tool for NASA. Sandra Bullock's character states, at one point, "I hate space."
The film is also, as mentioned, tense, even stressful.
One of the reason the film manages this tension is that it resists Hollywood's usually irresistible desire for a back story, for a love story or maybe a montage where Bullock tries on clothes. There are no flashbacks, no Apollo 13-like anguished family on the ground wringing their hands. The action takes place in space.
That puts the film, beyond the special effects, on the backs of Bullock and George Clooney. Clooney pays the story-telling, wisecracking commander or the mission, Matt Kowalski to Bullock's mission specialist, Ryan Stone. To say there is no back story isn't entirely accurate. We learn about these people how you would learn about someone in real life--through snippets of conversation (in this case under great stress). You do care what happens to them.
The film is about the action. And it begs the question; why do so many other films fail in this regard?. In many cases it is bad editing. In others someone just decides that MORE explosions is really all you need. Here the "explosions" happen at the right times and are not overdone. You even are given a sort of countdown to when they happen in some cases. It all ticks along like clockwork and the editing is so tight that you are never given a chance to relax. The special effects are not gaudy but truly give the feel of space flight. It seems real even when some of the action maybe strays a bit from reality (it IS a movie).
This isn't to give short shrift to the acting--both Bullock and Clooney do well in their roles, as fairly minimal as they are. Imagine them as people you just meet (in space). They do exactly what they need to in the roles.
It is a peculiar film to try to describe or recommend because it is so focused on what happens rather than the story or the characters. It is also one of those rare films that viewers should consider seeing in XD 3D. A great deal will be lost in 2D viewings of the movie. It is about the visuals.