Judging the success or failure of the stimulus spending has always been a difficult task. To evaluate it, you have to determine what would or could have happened had it not been implemented. That uncertainty allows both sides to play up the issue. The administration can say things would have been worse. The GOP can say things would have been better. It would seem a generous way to judge the stimulus' impact would be to evaluate it in terms of Obama's own projections.

In January, President-elect Obama said that unless drastic action was not taken (more stimulus spending) "we could see a much deeper
economic downturn that could lead to double-digit
unemployment
. Today after that drastic action was taken, President Obama said that unemployment will reach 10% before the end of the year.

Sometimes, politicians say things and the math is a little fuzzy. It isn't always fair to hold a politician to a statement like that. Perhaps his economic team's projections will paint a better picture for the stimulus' effect. They prepared a chart that shows the projections of unemployment with the stimulus and if we did nothing. This came directly from Romer-Bernstein study (pdf).
unemployment projections
So how does that shape up with actual unemployment numbers so far? Here's a chart from Innocent Bystandards juxtaposing the administration predictions with the real rate growth.

 

actual unemployment

FactCheck.org verified the numbers in the chart and also gives the Obama administration explanation, which boils down to "It's Bush's fault." (Isn't everything?) They also say that unemployment would be even worse without the spending, but as FactCheck.org says, there is "no way to prove or disprove such a
claim. What we can say is that in the three months after the stimulus
bill was signed Feb. 18, the economy lost more than 1.5 million jobs,
according to the BLS. So even if the president's 150,000-jobs [created or saved] claim is
correct, that's about 10 percent of the total jobs lost."