The worst period in american history? You've got to be kidding me. The great depression, the vietnam war, the late 70s, the civil war all pop to mind as times that were significantly worse than today.
Aside from having a press that has battered him at every turn, things haven't been that bad. It's not Bush's fault that Katrina hit new orleans, or that the people didn't evacuate when given plenty of opportunity. It's not Bush's fault that the housing market was as crazy as it was, or that companies gave bad loans. The war in Iraq has gone on longer than it was predicted, but shit, we still have troops in Germany, Japan, and Korea.
The bad gets exaggerated because the rhetoric is so divisive. There aren't riots, there's no food shortage, there's no draft, there's nothing that would historically count as a big negative. We had a stock market correction that has more to do with how the stock market operates than any indication of real problems in the economy. Yes, American automakers are struggling. Big shock there, they've been making poor decisions and turning out poor products for 40 years. Yes, the real estate market is struggling, because too many people were convinced they could afford to buy a house when they couldn't. There was some corruption that's being dealt with. As corruption goes, it's fairly minor when viewed through the eyes of history.