Rather than boom-and-bust, I would describe the entire history of the last four years in terms of 'hit and cluck.' After the massive hits of central bank liquidity in early 2009, late 2010, and late 2011, stocks and commodities have gone shooting up, if you'll pardon the pun. And once the hit has worn off, the inevitable period of clucking has set in, as summers 2010, 2011, and 2012.
Leaving aside the bigger issue of whether it is healthy for markets to exist from one fix to the next, periods like the present undoubtedly make it harder to trade. For starters, erratic movements make the resulting signals more frequent and less trustworthy.