A lot has been made of the contentious primary season in the Democratic Party (negative campaigning and botched primaries in MI and FL), but I think that the race has sharpened both Clinton and Obama and will better prepare who ever wins the nomination for the general election.
Both candidates have done a great job grabbing the headlines away from the Republicans allowing the candidates to define themselves on their own terms while lobbing repeated criticisms at McCain and Bush's policies. Unlike the press and many Democrats (according to the press) I think that a nominee will emerge in the weeks that follow and the party will be better for it.
All one has to do is look at how much money both candidates have raised and compare that to the money the Republican Party has raised and one gets a sense of how much people want a change at 1600 Pennsylvania Avenue. Who can say for certain what will happen in November but with Clinton and Obama collectively raising $60M in the month of March after several months of record-setting fund raising, I can not help but be optimistic and excited about the campaign.
I really do think that both candidates have inspired an entire generation and political science teachers will for years refer back to how history was re-defined when Clinton and Obama ran a hard fought (and sometimes bruising) race for their Party's nomination.