I've watched both the original and the addendum. I take it all with a grain of salt. There are some valid points, and also many bogus ones. I really don't care about the movie either way. It is what it is. That's fine. Believe what you want, I'll believe what I want.
What I dislike is when people criticize me for not thinking it's the most eye-opening, life-changing movie ever. It's a movie that asks you to question the entire fabric of society. Yet it's been my experience that when I even slightly question the validity of this movie supporters get very defensive and all of a sudden I'm a "sheep".
So questioning society as a whole = good but questioning a movie made by one guy with a biased viewpoint and questionable "facts" = bad. Makes perfect sense.
http://www.conspiracyscience.com/articles/zeitgeist/