1) Maybe you are equating QE with the whole crisis response?
Of all the emergency measures, ZIRP, bank bailouts, TARP and all the other lender of last resort programs even to companies like GE, and the massive fiscal deficits during the recession, even the Fed thinks that QE had by far the smallest impact but the largest cost.
2) QE alone is not sustainable. That is my point. It cannot consist without QF (quantitative firming) in the end, as the purchases will have to be unwound or run off. Therefore you cannot call QE a success before you haven't found out what the negative effects of the associated QF are.
If you really think that QE single-handedly saved us from a great depression, I would be very worried about the coming QF.
Or do you seriously think that the Fed can expand its balance sheet in perpetuity?
In the end, QE is another form of debt that will have to be repaid. So the whole thing is in effect a question of generational fairness. If you decide to borrow from your future to consume today, that's fine. But what we in essence are doing is to borrow now and tell the bank to collect from our not-even-born-yet grandchildren.