Watch a sufficient number of silent films—particularly in a block—and you do get a renewed sense of how silent cinema represents an art form that's almost completely distinct from the sound film. In a really beautifully made silent, you get the sense of the camera noticing more—certain nuances of gesture, movement. Bresson, I think, tried to recapture some of this "knowledge" with his particular cinematic strategies—closeups of hands and feet, and such. It's something I really love about silents, something I think contributes greatly to the almost mystic quality I find in many of my favorites.
Another thing I love about silent movies is Zasu Pitts. I write about her eloquence of gesture, and how beautifully it's captured in Frank Borzage's Lazybones, over at The Auteurs' Notebook.