Don't be put off by the trailer. Yes, Michael Moore does do his standard publicity stunt stuff but he also reveals some fascinating facts about how the current flavor of Capitalism in the US came to be.
There are some incredible foreclosure stories, the revolt of workers against an employer who laid them off with no earned benefits, more background to the $700 billion bailout, how ex Goldman Sachs execs now run the treasury and the revelation of the most disgraceful "Dead Peasant" insurance policies.
It is probably his best work. Not left -right, just the reality of where we are today. The problem he faces is that his early work (excluding Sicko which was also very Fair & Balanced in an unFox like way (I mean, it was fair and balanced)) was a collection of polemics and so he has written off a large chunk of the potential audience.
Go see it and watch as no-one on Wall Street can explain a Credit Default Swap (Wikipedia doesn't really help either).