Last I heard, it had halted the free-fall of the Dow and S&P -- stabilized financial institutions -- and put some kind of bottom under the housing market.
Since the 'leveraged' loss of capital from money supply approached $4 trillion, that stimulus itself wasn't enough to fully plug the hole. Lending is still difficult to get, for small business & residential.
If the stimulus had been excessive, we'd see inflation & low unemployment. We don't.