Olaf Stampf of Spiegel has an interview with German astronaut Ulrich Walter about Gravity, which was also reviewed by Buzz Aldrin. An excerpt:

“Spiegel:

In Gravity, Sandra Bullock plays an astronaut who gets separated from her shuttle and ends up floating in space, completely untethered. Would it be possible to save an astronaut in such a situation?

Ulrich Walter:

Yes, in principle. These days, every spacesuit is outfitted with a small jetpack. The pack’s range, though, is only about a kilometer, so it wouldn’t be possible to fly tens of thousands of kilometers to the ISS, as the characters do in the film. In real life, everyone involved in that disaster would have died. 

Spiegel:

It doesn’t sound like a very nice way to go, drifting through nothingness in a spacesuit, waiting to die. 

Ulrich Walter:

On the contrary! When you’re slowly running out of oxygen, the same thing happens as does when you’re in thin air at the top of a mountain: Everything seems funny. And as you’re laughing about it, you slowly nod off. I experienced this phenomenon in an altitude chamber during my training as an astronaut. At some point, someone in the group starts cracking bad jokes. Our brains are gentle with us. A person who dies alone in space dies a cheerful death.” (Thanks Browser.)