The US Federal Reserve's Open Market Committee meets again this week, and is widely expected to announce the end of its third round of money printing, dubbed "QE3".

Over nearly six years, the Fed has injected $3.6 trillion into the US economy through so-called quantitative easing, buying government bonds and other securities from American banks in an unprecedented stimulus program.

In that time, the US economy has gone from the near collapse of its financial system and a 6.3 per cent annualised economic contraction in the December quarter of 2008, to a moderate, albeit fragile, recovery.

Unemployment is below 6 per cent for the first time in six years, and the US economic growth rate has averaged 2.3 per cent since 2009.

"The economy seems to be ticking over at a reasonable pace," said Dr Shane Oliver, chief economist at AMP Capital.

"Whereas, when you look at other countries, for example the Eurozone by contrast, they haven't used quantitative easing like the US and their economy has paid the price for that with 11 per cent unemployment."

The Fed has been winding down – or "tapering" – QE3 since January.

A lot of money for little growth: Das

However, despite the economic gains since quantitative easing started, some argue it has done more to stimulate financial activity, rather than the real economy.

"In 2012/2013, the US was growing around about 2-3 per cent, which is between $500 billion and $600 billion of additional production of goods and services," said Satyajit Das, author of Extreme Money.

"Now to get that you needed roughly a new injection of money between $1 trillion and $1.8 trillion to create a very modest amount of growth."

Critics, including Rupert Murdoch and now the Treasurer Joe Hockey, also blame quantitative easing for widening the gap between rich and poor.

But perhaps the biggest fear is that quantitative easing may be sowing the seeds for the next crash.

"People forget that QE has actually helped boost the US stock market by a factor of three from its nadir in 2009," observed Satyajit Das.

"But the problem is this is unsustainable because those prices have lost all sort of touch with the reality of earnings."

Property prices in other markets, such as Germany, Canada, New Zealand and Australia, have hit record levels as the loose money from the US spills into other parts of the world.

In the US, where the sub-prime mortgage meltdown originated, a debt market bubble once again appears to be inflating.

A record $360 billion worth of junk bonds were issued last year in the US, as lenders chase borrowers in riskier areas, including car loans for customers with bad credit records.

While acknowledging that QE has its shortcomings, AMP Capital's Shane Oliver says the world is a better place because of the program.

"If the Fed didn't do QE, you potentially would have had 20, 25 per cent unemployment, which would have made life very tough for the average American worker," he speculated.

"So I think you always have to compare that to what would have happened in the absence of this action."