All elections are ultimately more about the person than the ideology of a party, no matter what the parties say.
Obama was a brilliant candidate.
Sure he was young (like JFK and Clinton), and sure he was inexperienced on the national stage (but more experienced than Palin), but the intelligence he possesses and the temperament he displays more than made up for that.
The voters who took the time to really get to know Obama's life story and learn just what qualities he possessed knew he would make a great president. In spite of Republican attempts to paint him as a radical, he was basically a decent, moral patriot. Married to a brilliant woman, father of two beautiful girls, having lived an exemplary life, full of accomplishments, Obama was able to fend off the criticism mostly by rising above it and by never attacking in kind.
Throughout the campaign, Obama handled vicious attacks regarding his limited association with William Ayers, and his spiritual connection to Rev. Wright. The first he mostly ignored, the second he neutralized with a brilliant speech on race. And while he fought vigorously with his opponent on the issues, he never once personally attacked him. In fact, in every speech where McCain was mentioned, Obama talked with great respect about the sacrifices McCain had made for the country. His respectfulness in talking about his opponent, his friendly demeanor in the debates (when McCain's obvious contempt for Obama showed in his refusal to look at him, his eye rolls, and his language) only confirmed the decency and even temperament of the man.
Obama's decency went beyond his treatment of his opponent, however. Obama possesses a kindness and empathy that he got from his mother. Obama often references his mother, and how the thing that would make her most angry was when he would treat someone badly. She was forever insisting he put himself in someone else's shoes. This empathy, so obviously missing in the Bush administration, is something the American people, who are basically a giving and kind people, were pleased to see in a presidential candidate.
Obama's temperament and decency were two thirds of the equation. His competence and intelligence were the third. After eight years of a bungled presidency with an incompetent and shallow president, American was hungry for someone with intellectual depth. Obama, first in his Harvard Law class, with a reputation for curiosity and listening, shows intellectual gifts we have not seen in a long time. And his thoughtfulness when confronting a problem is a refreshing contrast to Bush's governing by gut instinct, which has been such a disaster.
After eight years of Bush, America wanted a smart and competent leader, a decent and caring leader, and a steady leader.
They got all of those in Obama.