The book presents a pretty simple law of self improvement called the Law of Attraction which Byrne says has been suppressed for over 3,000 years and is only known by the wealthy 1% and great men throughout history such as "Plato, Newton, Carnegie, Beethoven, Shakespeare, and Einstein." It says that believing that positive things will happen will make it happen for you with wealth, health, and relationships and believing negative things will happen will make the opposite happen. It goes on to present that secret in DaVinci Code/Scientology fashion with lots of testimonials and graphics but little hard data to show how the law of attraction always works. The experts in the film even say that "the anti-war movement creates more war." Here is trailer for the film. The author is seen very little in the film.
The book has it's critics such as Barbara Ehrenreich who discusses her own struggle with cancer and how not being positive all the time helps her. The problem with relying on testimonial evidence alone is that it's always possible to find one contradicting your theory. The film presents no evidence of how this secret was suppressed all these years.
A closer look at the historical figures presented in the film and book shows that few of then had full happy lives. The one who comes closest is Plato and that is only because he lived thousands of years ago and we know so little about his relationships and what sort of man he was. Ludwig van Beethoven had a miserable life with many relationship, money, and health problems. Isaac Newton was "not a pleasant man" as described by Stephen Hawking (he holds the same professorship that Newton did) who never married and took pleasure in crushing his rivals. Andrew Carnegie may have been a good husband and father and did lots of charity work but he also ruthlessly crushed the Homestead Steel Strike and was negligent in the Johnstown Flood with crony Henry Clay Frick. William Shakespeare is another about whom there is little known and some controversy so I will not address. Albert Einstein like the others did excel at what they were good at but you would not want to be married to him.
There is always a risk of disaster and the chance of success. You can take steps to minimize the risk and maximize the chance but can never eliminate either. The passengers and crew on the Titanic had lots of positive energy and optimism but were oblivious to the risks that icebergs posed and we all know how that turned out (see my post Titanic Perspective if you don't for a review of this and Andrew Carnegie's role in the Johnstown Flood). I'm all for having success but at who's expense? Solutions can be found to the world's porblems but by realistically thinking through the risks and chances. It gives the secret as the reason for "the richest 1% controlling 96% of the world's wealth" when Ehrenreich and other social critics would give very different reasons. The Secret has definitely made Rhonda Byrne very wealthy.