The fuel the movie has, apart from the visuals, is Sandra Bullocks' emotions, and it's just wasn't enough. Maybe it's because there is no plot, though in my opinion, Sandra Bullocks' character wasn't very interesting and intriguing, and I didn't care much about her. I really hated her constant whining.

The supposed to be tension, was very artificial. The director just threw more and more obstacles, instead of building a tension around a character. I wasn't involved with the characters' emotions. I thought they were artificial either.

While, I don't think that the actors, Clooney and Bullock, made a good job, I think that the director is the one who totally blew it up. Sorry, but even if he succeeded in making cash for the production company (by adequate trailers and a very aggressive promotion), in the long run, it will be regarded as a stain on his career.

Like Avatar, Gravity was attended mainly because of its' visuals. But Avatar had enough plot and character development to sustain the visuals, while Gravity had none.