There has never been and never will be a perfect person or a perfect leader. You have to admire a person willing to take the leadership role and all the abuse of the people he can't please all the time. It's a MASSIVE undertaking to lead a country and you are at the mercy of all the general public and your advisers and Senators or MP's and on and on and the whole political machine.
Then there is all the money and power and influence exerted by different religions and powerful companies (like the oil companies - Bush!-don't get me started!). I would not want to be in the business of politics, period.
However, I do think Obama has done a good job over the past 4 years and has generated great changes in the U.S. I hope he is re-elected.