Or, another opinion is that the stimulus worked, but wasn't enough. Considering most Republicans refused to vote for it, surprising anything at all got through.
"Many economists thought the stimulus too small, not too big. The bill funded only a fraction of the infrastructure projects listed by the American Society of Civil Engineers as in need of construction or repair. Worse, the projects did little to stir the imagination of the public. Some of this was inevitable; necessary repairs of sewage systems would never be sexy. But with the exception of $8 billion for high-speed rail, the first such investment ever (placed in the package by Rahm at the eleventh hour) and pehaps some science projects that bore great fruit, it was hard to think of projects that historians would look back on in twenty years and say, "That's what Obama got for his trillion dollars back in 2009. He would have to settle for preventing another Great Depression". - "The Promise" - Jonathan Alter
"Those answers began in the Recovery Act, a grab bag that would never get proper credit for being one of the most important pieces of legislation in a generation. Along with the bank rescue, the ARRA kept a recession from becoming a depression. The extension of unemployment benefits for thirty-three weeks, expansion of food stamps, and $50 billion in stabilization funds to states and localities (which prevented hundreds of thousands of layoffs) all kept the economy from cascading downwards.
Michael Walman, Bill Clinton's former chief speechwriter, believed Obama's big political misfortune on the stimulus was that the budget rules required putting everything in one big package. In fact, it was five landmark pieces of legislation in one. If the bill had been split into the biggest tax cuts for the middle class since Reagan, the biggest infrastructure bill since the Interstate Highway Act in the 1950's, the biggest education bill since Lydon Johnson's first federal aid to education, the biggest scientific and medical research investment in forty years, and the biggest clean energy bill ever, then Obama would have looked like Superman, or at least more like FDR."