It's a Michael Moore movie, so the film making will be technically excellent, the politics will be leftist, the arguments will be tenuous, and the tactics will be questionable. That's pretty much all you need to know.
Look, I've defended Moore before, and I tend to be sympathetic to leftist causes. And he makes some excellent points here. The comparisons of modern America to the declining years of ancient Rome are apt, at least on the surface. And he gets some juicy sound bites from a pro-capitalist who argues that capitalism is better than democracy. To extend the metaphor, democracy might sometimes be two wolves and one sheep deciding what's for dinner, but capitalism is often two wolves vs. a hundred sheep and the wolves still decide because they control the means of production.
He also gets some great sound bites from religious figures who claim that capitalism is inherently evil (his re-dubbing of a scene where Jesus will only heal a cripple if he pays for the costs out of pocket is pretty funny), although at the same time he sort of goes off the rails with a radical "we must completely destroy capitalism" message.
Moore goes on to suggest that capitalism must be replaced by something else, and that something should be...democracy. I guess he didn't have the balls to say he really wants socialism/communism. Although he does gleefully let slip that a recent poll suggests opposition to socialism/support for capitalism in the U.S. is at an all-time low, and he does play a swingin' version of Los Internacionales over the end credits. Anyone with eyes even a little bit open will realize what he really wants. And again, I'm not unsympathetic I just wouldn't go as far as Moore.