I see it as nothingness, that people are left feeling emotionally empty as well as there physical surroundings being empty - not as in that there is no physical structure around, but that there are perhaps no people, that you are just left to wonder without cause. But, it could be that there are others around, but you don't mix with them and you all are on your own.
I don't like to think of Hell much to be honest, so I don't have an exact idea in my mind of what I imagine it to be like. But, I can't remember the name of the film - with Will Smith I think, where he finds himself alone, no one around. I imagine that to be like Hell. Just emptiness and loneliness.