I can imagine this is a very enlightening documentary if you're completely clueless about how Washington DC works, and therefore have a completely Pollyanna opinion of government.
I don't know too many people like that these days. In fact, most people are deeply cynical. The only ones that aren't are the ones who find it confusing and just don't care.
As an unchallenging, unprobing view of how lobbyists work in Washington that pretty much anyone could understand, this isn't a bad doc. It's not very probing, doesn't investigate anything not considered common knowledge by anyone who follows the news, and is unlikely to cause any strong reaction. It's adequately produced, along the lines of a local PBS special. It's also fairly non-partisan (it barely acknowledges the existence of parties). Perhaps it might be of interest of Europeans who occasionally look into American politics with a sense of schadenfreude (the producer/director is British), but I can't imagine anyone who's not turned off by the subject matter being all that enlightened by it in this country.