Just to clarify, there are 3 basic things required to pass legislation here(not counting judicial precedence) We have the House of Representatives, Senate, and the President. Right now, the democrats have the Senate, and the Presidency. Republicans have the House. For two years of the presidents term, the democrats had all three. For those two years, they could effectively do whatever they wanted. Once the people saw what they had to offer, the next election swung republicans into the house. While the republicans had no hope of getting any of their "debatable" ideas passed, they at least had the ability to prevent the democrats from doing the same thing. In my opinion, this was, at the very least, what the people hoped for-stop the madness so to speak.

Obviously the above explanation doesn't factor in everything, but I think it's a pretty good overview for someone who isn't familiar with our system. In all honesty, I would not be surprised if the next four years have a similar tone should Romney win. People are just so fickle.