The Financial Times has a great interactive graphic that does a fairly good job of explaining quantitative easing, both in terms of the risks and how it may be able to stimulate the global economy. While I think the piece brings up some valid points, at this point I'm loathe to pin the hopes for economic improvement on one particular strategy. Especially considering the risks involved in trying to address economic woes via simply creating new money, with respect to currency devaluation, inflation, etc.
More importantly I think the fatal flaw inherent in many of the tactics being used by Central Banks (at the moment) is that they're more aimed at treating symptoms, as opposed to addressing root causes. In many ways it's analogous to trying to treat broken legs with Advil, rather than setting the leg, putting a cast on it and waiting for it to heal. I say this is because the goal seems to be to stimulate confidence as opposed to addressing the reason(s) why people have lost confidence in the first place.
So while some degree of quantitative easing may be necessary, I think we have be mindful of what got us into this situation in the first place and work on addressing those systemic issues as well.
I.e. we should hand out Advil to the people with broken legs, but let's also set their legs, put casts on them and get them scheduled for rehab once the legs heal.
Disclosure: at the time of publishing the author didn't own a position in any of the companies mentioned in this article; the ideas expressed are solely the opinions of the author and shouldn't be viewed as financial or investment advice.