Think about the characteristics of Elizabeth and Darcy at the beginning of the novel and at the end. How do they change throughout the course of...

Both Elizabeth and Mr. Darcy change quite a bit over the course of the novel.  Darcy realizes that his pride in his dealings with Mr. Wickham after Wickham tried to elope with Darcy's sister, Georgiana, actually enabled Wickham to take advantage of another girl: Lydia Bennet.  Had Darcy exposed what kind of man Wickham really was, Wickham likely would not have been able to do this.  Further, he realizes that he ought not to have...

Both Elizabeth and Mr. Darcy change quite a bit over the course of the novel.  Darcy realizes that his pride in his dealings with Mr. Wickham after Wickham tried to elope with Darcy's sister, Georgiana, actually enabled Wickham to take advantage of another girl: Lydia Bennet.  Had Darcy exposed what kind of man Wickham really was, Wickham likely would not have been able to do this.  Further, he realizes that he ought not to have gotten in between Bingley and Jane.  He also understands how unspeakably rude he had been and that he had "been a selfish being all [his] life."  By the time Elizabeth went to Pemberley, however, Darcy says that he wanted to "obtain [her] forgiveness, to lessen [her] ill opinion, by letting [her] see that [her] reproofs had been attended to."  He stops seeing himself as superior to her and begins to think of how he might please her.

Elizabeth also realizes that she has judged Darcy too harshly.  He virtually saved her family from ruin by forcing Wickham to marry Lydia, paying him in lieu of any dowry from the Bennets.  She realizes that, instead of finding him the last man on earth that she could ever want to marry (as she had months before), she feels a great deal of "gratitude" for Darcy's generosity, propriety, and discretion.  

It seems that Austen is pointing out the faults of both.  We see how excessive pride and willing prejudice can prevent, or at least delay, a realization of how well-suited two people might be for one another.  Elizabeth and Darcy, we might assume, will have an equal marriage based on mutual love and respect.  It would be sad, indeed, if their mistakes had prevented their happiness.