Great episode. I love shows that have to do with life after death in any way possible.
What is so great about this episode? Well I love the story first of all, I love the setting which is a nineteen century city, tight streets, horse carts and a pact that must last after the grave.
My favorite scene is when all the spirits let themselves be seen but they are all a green smoke in the air. This is one of the scariest moments in the Twilight Zone universe in my opinion.
I think this episode deserved another 5 to ten minutes to know more about the society members and their lives.