I can't imagine what heaven is like, but I think I know hell.
People always think of fire and demons with pitchforks. I don't see it that way though, physical pain is nothing next to mental/spiritual suffering.
To me hell is just a land of isolation. I think in hell there is nothing. To be aware of everything that's happening, but yet nothing is happening. You can't fight against it, because there's nothing to fight against, so you fight against yourself. In hell you wish you were dead, you're suicidal, but there's no way out. An eternity of nothing, not even physical pain to remind you of the feeling of being alive.
Maybe that's just my hell though.