Politicians will break your heart, every single time. Anyone who becomes President has to be an egomaniac who appears humble, a megalomaniac who has to work in a system that is designed not to let anything happen, a manipulator who has to appear honest and straightforward, a pragmatist and cynic who has to appear to be an idealist, and a stark raving schizophrenic.
And their hubris overcomes them, each and every one.
Just remember the disappointments that Clinton and Carter were, unable to handle Congress (or, in Clinton's case, himself). Kennedy gave us the Bay of Pigs and started the real push into Vietnam. FDR sent Japanese Americans into internment camps. Reagan sold arms to Iranians in exchange for hostages, and used the money to fund the Contras.
I like Barack Obama. I gave him a lot of my time and money. He ran the first open source presidential campaign. He's not a magician. The problems that Obama faces are enormous. We haven't just voted away the last eight years, or the last 16 years of fractious partisanship.
On the plus side, he is a smart guy, understands the magnitude of the challenges, and is a change from the disaster of the last eight years. We'll see what happens.