I think Mark Thoma shows the key factor for the lackluster impact of QE2 on overall economic activity:
To gauge the success of a policy, it has to be measured against the policy goals. Although QE2 did stimulate economic activity, the primary goal was to prevent deflation, as Fed Chairman Ben Bernanke made abundantly clear in his last press conference. By this measure, the program was a smashing success. Inflation expectations — as measured by 10-year inflation-protected Treasury securities — had plunged to 1.49 percent before the Fed’s actions last fall, and subsequently rebounded as high as 2.64 percent.
When you see what happened in countries like Sweden , Poland or Australia the only
conclusion is that Bernanke showed very little ambition. But he was true to
himself – an inflation targeter as a means to avoid deflation. The real economy
is not his province!
Update: More evidence that QE2 was just an “anti deflation device”:
“I believe it is quite accurate to say that many of us were concerned last summer about the danger of the U.S. repeating the Japanese experience, that those concerns have since been reduced, and that the stance of the Federal Reserve is one reason those concerns have been reduced. This does not mean that the Fed solved all our problems, and I never believed that it could. But I believe the Fed did avoid making our problems worse”.