The polls are in on the publics response to Obama's first State of the Union speech, and the numbers pretty much speak for themselves.

According to the latest Gallup poll, Obama's job approval is still under the half-way mark, at 48%.  Via LifeNews:

In the three days following the speech, Gallup shows Obama with a 48
percent approval and 46 percent disapproval rating -- unchanged from
before the address.

Philip Klein, a writer at the conservative magazine American Spectator gives
his insight on the poll.

"Going into President Obama's first State of the Union speech,
Gallup noted that annual speeches to Congress rarely affect presidential
approval ratings (in large part because the audience tends to be skewed
toward those who already support him). It turns out that despite his
oratorical skills, our current president is not different in this
respect from his predecessors," he writes. ...

Klein continues, "What this tells us is that Obama has reached the
point in his presidency at which he'll no longer be able to boost
public opinion through talking -- he's being judged based on his objective
performance. Monthly job reports will have much more impact on public
perception than anything he can say or proposal he could make."

As the saying goes, "actions speak louder than words".

Pollster Scott Rasmussen finds that

The president in the speech declared that his administration has cut
taxes for 95% of Americans. He even chided Republicans for not
applauding on that point. However, just 21% of voters nationwide
believe that taxes have been cut for 95% of Americans. Most (53%) say
it has not happened, and 26% are not sure. Other polling shows that nearly half the nation’s voters expect their own taxes to go up during the Obama years.

The president also asserted that “after two years of recession, the
economy is growing again.” Just 35% of voters believe that statement is
true, while 50% say it is false.

Obama claimed that steps taken by his team are
responsible for putting two million people to work “who would otherwise
be unemployed.” Just 27% of voters say that statement is true.
Fifty-one percent (51%) say it's false.

That pretty much defines a "credibility gap".

Another thing we seem to be seeing here is that, by way of his actions (or inactions) over the course of the past year, Obama has lost those in the middle who supported him because they projected what they thought he was (or wanted him to be) on the blank slate that his campaign presented to the public.  Which is another reason why he stayed as far away as possible from controversial details.

His campaign was built around what he was not, rather than what he was.  Meaning, he was "not" George Bush, and he "was" pretty much whatever you wanted him to be.

But as the polls (and election results in Virginia, New Jersey and Massachusetts) have borne out, it's taken less than a year for people to catch on.