I found part 1 to be very interesting but there was nothing very earthshaking for me in it. I already knew about the pagan roots of many of the things in the Christian religion -- I just didn't know that it went as far as it does.
Part 2 is about 9/11. It seemed fairly believable but I've come across too many off-the-wall 9/11 conspiracy nuts to be able to take it without a huge dose of salt.
Part 3, however, was something else entirely. It talks about how the international bankers are controlling the world and it all had the ring of truth. I had previously come across many of the claims in it, but a lot of it was new. The Federal Reserve Bank (which is not Federal, has no reserve and is not a bank) engineered the Great Depression as well as other financial crises. The entry of the U.S. into the major wars of the 1900's were all setups because war is very profitable for bankers. George Bush's grandfather had a bank that laundered money for the Nazis in the 1930's. If you want to get very worried, then google 'North American Union'.
Zeitgeist - The Movie, 2007 has a lot of information as well as the movie as a downloadable .avi file. I would urge everyone to watch the entire movie and then decide for themselves how much truth there is behind the claims.