Great Expectations is a coming of age story that revolves around the life of one man Pip.  From the time he was seven years old until he was in his mid-thirties, Pip shows us the important events in his life that shaped who he became.  Along the way, he acquires a menagerie of different acquaintances and friends that influence him in his decisions and goals for his life. 
Pip's story has one main point: no matter what happens to a person in their life, a person cannot change who they are inside.  Pip does not realize this at first however.  From the time he met Estella and Miss Havisham, Pip tried to change himself to fit a mold that he thought they desired.  He began simply, learning to read and write.  As time went on, and his circumstances changed, Pip pulled farther and farther away from where he came from and in doing that, who he was.  Through his story, people see that this type of change brings him no joy, and in Pip's case, exactly the opposite.
Pip's story is not about living happily ever after with Estella.  Dickens never tells us what happens, if anything, between them in the end.  He leaves it only that they remain friends.  There is a purpose for this.  Dickens novel is about Pip's quest for Estella's love and what he is willing to do to gain it.  The story is never about the love itself.  We can see this because in the majority of the story, Estella is only present in Pip's heart and thoughts.  The actual interaction between the characters Dickens keeps at a minimum. 
Great Expectations is a story that the public can relate to because at some point, everyone goes through the struggles that Pip must battle.  It shows that possessions and wealth do not change who people are inside, and that finding one's self can be a long tedious process until finally the mists rise and everything becomes clear.