As summarized here, a report from the non-partison Congressional Budget Office concludes that the American Recovery and Reinvestment Act, commonly referred to as "the stimulus," led to an additional 1 to 2.9 million jobs.
The stimulus was widely criticized as too small (for example by Paul Krugman) or as a complete waste (for example by large parts of the Tea Party). In fact, it was too small to offset the massive job losses, including the huge workforce reductions in cash-strapped state and local governments, but it would have been astonishing if no jobs had resulted -- obviously, the money in question had to wind up somewhere.
It's long been clear simply from a look at jobs numbers that there was a growing net reduction in the U.S. workforce since the start of the Great Recession, and not long after the recovery act passed, the number of jobs started to grow again. The rate of job growth is inadequate, and unemployment is still far too high, as Krugman and other economists predicted. But it's good to be reminded that the stimulus, however undersized, did achieve something worthwhile, including paying for a lot of infrastructure work we needed anyway.