Those who want Obama to completely disregard the political reality in Washington and the world are running toward the same cliff the Republicans fell from. Until I see us moving the wrong direction, I approach supporting Obama under the assumption that he has the correct goals and is doing everything in his power to meet those goals without running into a backlash or a speed bump. So even if he does some things I may not consider ideal, I assume he does so out of necessity rather than choice. This is not an absolute trust and if he begins to move in a direction or at a speed in which I'm not satisfied I won't hesitate to withdraw my support. Still, it's important to consider the context of his actions.
When Barack Obama decided to keep Gates at SecDef, it seemed to many like a poke in the eye to the netroots and those progressives who helped raise him to a seat in the Oval Office. This ignores the fundamental reality within which he must operate. Not only does he get what he wants from Gates, a withdrawal from Iraq and a renewed focus on Afghanistan, but he does so without aggravating those who seek to oppose him. Republicans are effectively isolated from opposing him on Iraq, freeing him up to focus on more pressing matters that will be sure to make the opposition actively try to stop him (The Supreme Court for example). This is politics. You isolate those who oppose you (whether by addressing their concerns, inhibiting their actions, or some other means of nullifying their opposition), while bringing along those who can help. Politics involves compromise, showmanship, subtlety, and pragmatism.
In the past a leader need only concern himself with a few powerful individuals. He could isolate individuals and neuter their ability to oppose him then convince enough of the remainder to go along without need of considering the broader population. Politics was almost entirely a personal undertaking with friendships and personal interests just as important as ideological differences, if not more so. Essentially, in a Monarchy the "constituency" was made up of only those individuals who had enough power to oppose him. The King need not worry about his subjects as they had no legal nor physical resources with which to oppose him. Instead, his opposition came from those who could personally affect him: the nobility with their own troops, wealthy religious officials, or his family and court. In truth modern politics isn't fundamentally different, it's still a largely personal affair when it comes to the actual act of decision-making and compromise, though the process has evolved considerably.
However, unlike a monarch, a modern leader gains his legal power by virtue of an election. Inasmuch as a senator or president must placate a colleague, offering compromises or gifts for example, he must also keep in mind those who vote for him. Politicians must avoid angering people enough that they vote for someone else. Still, even in a democracy the power of the voters is limited. The "popular will", so to speak, merely frames the debate, making proposals excessively unpleasant to the voters impossible to pass. Voters cannot control the debate, however, and the details are settled between decision makers with little input from their supporters.
Barack Obama's "New" politics must be understood in this context. Politics will always involve individuals; egos must be bruised or stroked, as the case warrants. As such, we cannot not expect him to do everything we would want in an ideal world so long as disagreements exist. Instead, the "change we can believe in" is the dramatic widening of the circle of people the president must isolate or convince. From the beginning, when the King had to concern himself with only the most powerful, this circle expanded to include a far larger group of wealthy businessmen with the money to change the game. It then expanded to an even larger group of informed land-owning white people with the votes to take the politician's job, and then still larger to those with the time and education to make an informed vote. Obama has caused this circle to expand further than ever before. We now live in a political landscape where, through the expansion of the internet and subsequent voice given to millions of people, a massive segment of the public has the ability to not only watch the process of politics unfold, but influence it through voting, writing, blogging, reading, and truly speaking to those who make the decisions in our world.
Barack Obama will not change people into something they are not, nor can he. However, he has brought awareness of our own power to affect change. He's shown those in power that we are more than simply votes, and that obfuscation and lies can only go so far when We The People have the means to unearth the truth, independent of the powerbrokers themselves. In this sense he IS the prophet the Conservatives sarcastically label him, as he's helped illuminate a process of change that was already underway.
Though he cannot promise to do everything we want, no one can. He has acknowledge our power, and he HAS promised to do everything in his power to enact what we want. I think that, at least, has earned him the benefit of the doubt.