There have been very good grounds to criticize President Obama's foreign policy so far. There will be much more to criticize over the next three and a half years.
But he is our president. We could be at an historical inflection point in Iran. The United States may be able to play an important role. The task now is to explain what the Obama administration (and Congress) should be saying and doing, and to urge them to do what they should be doing. Presuming ahead of time that Obama will fail to exercise leadership, and cataloguing this episode pre-emptively as another in a list of Obama failures, would be a mistake. The U.S. has a huge stake in the possible transformation, or at least reformation, of the Iranian regime. If there's some chance of that happening, and some chance of U.S. policy contributing to that outcome, we should hope Obama does the right thing, and urge and pressure him to do so--because then the United States will be doing the right thing, and the United States, and the world, will benefit.
This too is the role of a loyal opposition.