In my opinion, the US government works (or perhaps does not work) the way it should. What I mean by that is that the government often fails to work, but the failure comes about because of the way the Framers set the government up. I believe that each branch has its correct share of power.
We cannot say that either Congress or the President has more power than the other. They each have the power to cancel the other out. The Republicans who control Congress right now would love to repeal “Obamacare,” but even if they could get repeal past the Senate, there is no way President Obama would sign such a law. In turn, President Obama would love to get laws passed to fight climate change, but there is no way that Congress will let him do that. The Framers did not want either the President or Congress to be able to simply have their way and so they forced those two branches to share power. Major bills cannot be enacted into law today because the Framers set it up so that the two branches could cancel one another out.
Since you have asked this question less than a week after the Supreme Court ruled that there is a constitutional right to same-sex marriage, you might argue that the judicial branch has too much power. I would not agree. First of all, the Supreme Court has always had this power and has used it many times over the years without endangering our democracy in the long term. People who dislike the Court’s decisions get angry and argue that it has too much power, but it is just doing its job. If the Supreme Court could not make unpopular decisions, it would be worthless. It would not be able to stand against the elected branches if they took our rights away. In order for the guarantees of rights in the Constitution to mean anything, there has to be a judicial branch that can prevent the elected branches from violating those guarantees.
Furthermore, we cannot say that the Supreme Court has too much power. The Supreme Court can overturn laws passed by Congress, but only in special circumstances. It cannot just go in and fix Obamacare to make it better. It cannot fix our tax system. It cannot proactively make laws on whatever area it chooses. It does have power, but its power is circumscribed because it can only rule on cases brought before it and can only override the elected branches when the laws they pass are unconstitutional, not when the Court simply does not like those laws.
While others might not agree, I would argue that all branches have the amount of power they are supposed to have under the Constitution. I do not think any branch has too much power right now.