Frankenstein is a harsh story. It is filled with sorrow and anger, and characters often lash out at one another. The experience of seeing it as a stage show brought a new life to it. The actors let loose their characters' rage, and it was visceral.
I can't help but feel that theatre is unique in this quality. Movies are so dolled up that actors never really let go; everything is calculated and edited just right. A play, though, is severely stripped down. You don't have the background music or the panning shots or extreme close ups. And by removing all of that veneer, you can tap into that raw humanity that we rarely see let out.