In brief, Gravity concerns a routine space operation that goes horribly wrong. Sandra Bullock and George Clooney — virtually the only characters in the movie — are both great. I won't tell you much more because I don't want to spoil any of it.
I will tell you that it's superbly written — well researched, with deft characterisation — and has one of the greatest lines of dialogue in recent screenwriting history ("It's a little gloomy in here, isn't it?"). I just loved the script, which was written by Alfonso Cuarón and Jonás Cuarón. I respect their work so much that I learned how to put the accent over the "o" in their names. And the "a".
Alfonso Cuarón also directed Gravity and he has a long and distinguished track record as a director, most recently with Children of Men, one of my favourite films of all time.
A few other quick points about Gravity. It has a trailer which, rarely, doesn't give away too much about the film — unlike the trailer for the remake of Carrie which ploddingly, and reprehensibly, lays out the whole story of the film. (Presumably so as to ruin it for anyone not already familiar with the plot.) But the trailer for Gravity just gives harrowing and tantalising hints of what's in store.
Gravity is on release in both 3D and 2D. I saw it (twice) in 3D, which was fun but, for my money, didn't really add a great deal to the experience (though I have heard it is very impressive in IMAX 3D). I'm sure it would be just as much of a knockout in 2D.
The music score by Steven Price is also amazingly effective and adds considerably to the impact of this great movie.
And I just want to say that the ending of the film is one of the high points of modern cinema.
(Footnote: Jonás Cuarón, the director's son and fellow screenwriter has made a fascinating short film which is sort of a plug-in for Gravity, concerning simultaneous events on Earth.)
(All the images are from the ever-reliable, though ad-infested Ace Show Biz.)