There is a useful paper by Hiroshi Ugai, which finds mixed results, here is part of the abstract:
This paper surveys the empirical analyses that examine the effects of the Bank of Japan (BOJ)'s quantitative easing policy (QEP), which was implemented for five years from March 2001 through March 2006…
…because of the QEP, the premiums on market funds raised by financial institutions carrying substantial non-performing loans (NPLs) shrank to the extent that they no longer reflected credit rating differentials. This observation implies that the QEP was effective in maintaining financial system stability and an accommodative monetary environment by removing financial institutions' funding uncertainties, and by averting further deterioration of economic and price developments resulting from corporations' uncertainty about future funding.
[yet]…many of the macroeconomic analyses conclude that the QEP's effects in raising aggregate demand and prices were limited. In particular, when verified empirically taking into account the fact that the monetary policy regime changed under the zero bound constraint of interest rates, the effects from increasing the monetary base were not detected or smaller, if anything, than during periods when there was no zero bound constraint. The studies generally show that the QEP had a greater monetary easing effect than that stemming from merely lowering the uncollateralized overnight call rate to zero percent, while the effects in raising aggregate demand and prices nevertheless turned out to be limited…the substantial decline in responsiveness to monetary easing on the part of corporations and financial institutions resulting from their deteriorated core capital due to a plunge in asset prices played a major roles.