Disclaimer: I have very strong disagreements with the President and several of his actions, including the Patriot Act issue (among others). I also agree with many of his social views.
Considering the role of the President properly, including the ways in which certain latitudes of movement (i.e., the ability to fulfill campaign promises or advance new agendas) are circumscribed by congressional action, I don't think asserting that he could have done X were it not for Y is really something that falls in the whether-you-believe-it-or-not category. Not everything in reality is there for you to believe or not believe.
The President does not have the power to just operate in total freedom, doing as s/he will with the office. The President can advance an agenda, attempting to build congressional support, but then has to pretty much wait to see what happens. Where that agenda requires Congress to take it up and act, it's rather disingenuous to blame any sitting President.
Moreover, there is a vast disconnect between the structure and operations of government and the People's perception of its structure and operations. When a sizable majority elects a presidential candidate based on the promises made in his/her platform, [I think] they actually expect to see those promises fulfilled. Unfortunately for the voters, the President doesn't really have the actual power to fulfill most (if not all) of them. This is especially frustrating when one sees a historical moment that could be capitalized upon, but is then reacted to with all manner of obstructing and filibustering that the ousted party can muster (such as that of the GOP focused on their goal of making President Obama a one-termer).
So, a new President enters the office, flying into the White House from the lofty heights of the People's surging will, and then Congress decimates the euphoria by thinking that they can go back to politicking and just ignore that the People voted not just for the candidate, but for the candidate's platform. In this way, the onus is really on the President's party to move forward with legislation that embodies the platform. To this end, the Democratic Party did a poor job.
Of course, this cuts both ways and is a difficult reality. Voters expect to see a President's platform promises fulfilled, and rightfully so. But as far as those who didn't vote for the platform are concerned, it's a tough road that carries with it all manner of Tocquevillian tyranny-of-the-majority concerns. Were Romney-Ryan to win, I sure as hell wouldn't want to see the whole of Congress hunkering down to draft legislation that mirrors the GOP platform, because I find most of it to be utterly atrocious and unconscionable (particularly where social issues are concerned). I want Congress to resist rolling us back to pre-1964/1972 America.
Obviously, the President can reverse EOs from prior Presidents. This, I think, would be an excellent thing for Presidents to actually spend significant time doing. Not just the occasional reversal that we typically see. They could be undoing all the damage wrought by their predecessor insofar as the people have voted with a clear enough mandate for his/her platform as it relates to being opposed to certain prior presidential actions. This is why Gitmo is such a sticking issue (to me, at least).
But where the platform consists of items that require legislation, the President is much more hamstrung to fulfill these promises--which then makes for great, but utterly useless, campaign fodder for his adversary in the next election cycle.
All that said, presidential actions that speak louder than words (or platforms), are another matter entirely. President Obama's actions have, on the whole, brought America back into considerably better standing with the world community than it was under Bush. I've seen quite a bit of press in Europe given to discussions about how much more preferable Mr. Obama is to Mr. Romney. There are plenty of presidential actions that have nothing to do with certain legislative actions--and yet the typical election cycle inevitably focuses on presidential actions that relate to legislation instead of fulfilling the job of being the executive.