I think all political systems are flawed in one way. But one you could say with our system is, well, it is more stable. In a parlimentary system, you can have multiple parties competing, all with different agendas. Of course, they will be a coalition set up to run the government, but, as been seen in many countries (France, Israel, Canada), one party in the coalition has a disagreement with the other, they leave the coalition causing basically the collapse of the government, forcing new elections. This, sometime even within months of a previous election (i.e. Canada).
With the US system, only two parties can realistically win, and in turn, only one party has to worry about being in control (well, you do get situation where one party controls one branch, like the Presidency, while another leads the Congress. But still, it is one of those two parties leading). It's more stable so you don't have elections in random years. Sure, the two parties are, and can be terrible (which they are) but at least I don't have to worry about whether the government will be there for six months or three years either.
As for the Presidency, I won't get too much into it since well, I always get in trouble when politics is brought up. I'll just say that I'm glad Kerry didn't win the last election. No, I don't think Bush is that great either. I just think that Kerry was NOT the man that should replace him. IMO, he was a huge joke.
If anything, I thought both choices were terrible. I just felt that Kerry was the worse of the two.