What is the moral lesson of Great Expectations and how would you evaluate the novel as a whole?

There are many possible moral lessons that you can take away from this book, but the main push is centered around the fact that money can't bring you happiness.  The only thing that can truly bring you happiness is loving relationships with your family and friends.  Think of Pip's experiences as a whole, and how after his inheritance, he was always miserable because he felt guilty for alienating Biddy and Joe.  He got into debt quickly, felt constantly pressured because of it, and had no purpose or direction in life.

It was only after his money was no longer that he was able to reconcile himself to his family and find a profession that gave him happiness and purpose.  With the money, he felt no drive to succeed of his own merit, and was embarrassed by those in his life that weren't up to his "station".  Dickens seems to make the point that kindness (as in kindness to Magwitch), family and friends, and personal achievement are the sources of happiness in this world, and how money just makes people pretentious, vain and often immoral.

To evaluate the novel as a whole, look at things like the theme or moral, the writing style, the characterization, and its success through the years.  I provided some links below that might be helpful to you as you do this.  I hope that these thoughts helpd; good luck!