I believe that heaven is not some perfect version of earth. Well, I do, but more than that. I think that humanity has a natural link to God. Something that is a part of you that you take for granted, don't even realize is there. And, like a limb, when it is taken away, you feel the loss acutely, and how much more-so would be a blow to your very soul? In that way, when the Bible says that in Hell there will be "weeping and gnashing of teeth," it is my personal that you are completely and totally cut off from God. I think that pain is what "Hell" will be, not a burning underworld, but a dark, solitary eternity of complete and utter loneliness and isolation.
In the same way, though heaven, I think, will be a perfect place, it will also be a perfect connection with God(that is the best way I can think of to put it). To be in the presence of a perfect being, forever, well, I can't think of anything more wonderful.