I think that's a good question. But part of the problem is that people want to blame or credit the President with too much. When you think about it, when the economy really does depend upon who sits in the White House, we're all in trouble no matter who sits there, because the whole point of our Constitution was to PROHIBIT the government (in all branches) from gaining too much power over our liberties.
The reality is that the President is perceived to have more power than he has, and more attention needs to be paid to Congress, which is the primary culprit in most of what goes wrong with government. Other big culprits include the runaway bureaucracies within the Executive Branch, but which the President has little true influence over, since the bureaucrats last much longer than any administration.
In particular, we are facing the problem of government controlling not only more than it ought to, but more than it is capable of, and our current economic crisis, as well as its disastrous aftermath of bailouts and debt, are a direct result of gov't simply being incompetent. I disagree strongly with the Obama administration, but I am less worried about him (he'll be gone in a few years, no matter what) than about what Congress has unleashed upon us in the way of new agencies and new legislation.