I was surprised by how little the film relied on flashbacks. When I heard the film mainly took place in the main character's head, I assumed that meant it would cut back and forth between The Rock and his childhood -- or something.
It doesn't. The closest film I've seen to it was The Diving Bell and the Butterfly, which also used visual imagery to evoke mental states, but it also relied heavily on voiceover, which 127 Hours doesn't.
Anyway. It's a good film. It's worth seeing, and because of the gorgeous scenery, is probably better seen on the big screen. The Scene is not as tough to watch as you've heard.
I also checked out the animated Oscar films. I found Shaun Tan's The Lost Thing absolutely charming, but I think the award will probably go to The Gruffalo, which was the crowd favourite. Madagascar, carnet de voyage might take it as the outside artistic favourite.