A study by Congressional Quarterly showed that Obama did better than any other president since Truman in getting congressional votes when he took a stand on an issue.
Here's the relevant graphic:
Many on the left seem to think that Obama can pass legislation by fiat or that he has plenty of leverage to "twist some arms" and get Republicans and/or moderate Democrats to vote how he wants them to vote.
Now, we no that even "I make the rules here" George W. Bush had only limited success forcing legislators to vote his way.
There are only so many carrots and sticks available to the administration and they still want to get a lot done even after a healthcare bill passes, as it should fairly soon.
Now of course no president can absolutely deliver on all promises unless they really have a Congress that agrees with him/her on all the issues. Obama still has a lot on his agenda. Of course, each "promise" is really a commitment to get things done and there are still other "promises" that need to be kept. Unfortunately, the ultra-progressives will make as much hay as the right-wingers if Obama does not keep a campaign commitment to the letter. Never-ending conspiracy theories will spring up predictably if that happens.
Again, Obama is the best thing to happen to progressives since LBJ's Great Society legislation. Actually even since the New Deal. No other president has committed to as much social reform since the days of the Great Depression.