The nature of our voting system means that we gravitate towards only two parties, and those parties end up defining a very thin and hazy line distinguishing themselves. It's not because they have to compromise - in fact we have to compromise a lot less than other democratic systems that sport way more than 2 parties.
The no pre-existing conditions clause, while important, is still a tiny part of a pretty tame piece of legislation. It really doesn't change much.
My point is that it really didn't matter who got elected president in this cycle. Yes, most of what gets done is a compromise, but that's the point - neither party controls congress, we're not going to see any crazy legislation. The actual executive branch under Obama behaves pretty much the same as before.
Maybe I'll be proven wrong, we can check back in 4 years.
You'll never be "proven wrong" because the differences in parties are subtle in some areas. You'll never know what would have happened if the other party got elected, as well. The compromising nature of our form of government makes it seem as though both parties are one and the same, but that couldn't be further from the truth.
Within the last week, Obama has made it clear three times that if Republicans try to use the middle class as a hostage to keep taxes low on the rich, then he's going to let the taxes on the middle class end as well. That's certainly not something you'd see under a Republican president. The medicare expansion, its gigantic loopholes and the inability to pay for it that were passed under Bush? Opposed by democrats, but passed because it was somewhat compromised. They had to water it down. That's the difference.
If you look at the end result of legislation from both parties you're going to find a similar result, but the difference comes down to trying to get your party the bigger portion so they have to compromise less.
The best way I can think to explain this is coloring. You had a yellow crayon, a red crayon and a blue crayon. Now, the result is always going to be yellow-ish, but there are still definite and noticeable differences between yellow-red and yellow-blue. Perhaps not the best colors to illustrate my point, but it should get across what I'm trying to say.