I agree with oh_riginal. Though Star Wars is an action/sci-fi epic, you have to have a few scenes that focus solely on the emotional state of the characters. I think what makes the scene so moving (for me, at least) is that Luke has hit rock bottom - no weapons, one hand missing, can't climb, etc. The tension is in whether he has the strength to hold on long enough until Leia comes back for him - the pressure is completely on him. To me, this is much more intense and emotionally engaging than "I sure hope one of those TIE fighters doesn't shoot that wire he's hanging on."

Sometimes you have to have less action in order to tell a more powerful story.

@ Kapheen - thank goodness he didn't lose the will to live before Lando showed up. :)