Columnist Sebastian Mallaby of The Washington Post reacted sharply to Perkins' book:"This man is a frothing conspiracy theorist, a vainglorious peddler of nonsense, and yet his book, Confessions of an Economic Hit Man, is a runaway bestseller." Mallaby, who spent 13 years writing for the London Economist and wrote a critically well-received biography of World Bank chief James Wolfensohn, holds that Perkins' conception of international finance is "largely a dream" and that his "basic contentions are flat wrong". For instance he points out that Indonesia reduced its infant mortality and illiteracy rates by two-thirds after economists persuaded its leaders to borrow money in 1970. He also disputes Perkins' claim that 51 of the top 100 world economies belong to companies. A value-added comparison done by the UN, he says, shows the number to be 29.
Other sources, including articles in The New York Times and Boston Magazine as well as a press release issued by the United States Department of State, have referred to a lack of documentary or testimonial evidence to corroborate the claim that the NSA was involved in his hiring to Chas T. Main. In addition, the author of the State Department release states that the NSA "is a cryptological (codemaking and codebreaking) organization, not an economic organization" and that its missions do not involve "anything remotely resembling placing economists at private companies in order to increase the debt of foreign countries". Economic historian Niall Ferguson writes in his book The Ascent of Money that Perkins's contention that the leaders of Ecuador (President Jaime Roldós Aguilera) and Panama (General Omar Torrijos) were assassinated by US agents for opposing the interests of the owners of their countries' foreign debt "seems a little odd" in light of the fact that in the 1970s the amount of money that the US had lent to Ecuador and Panama accounted for less than 0.4% of the total US grants and loans, while in 1990 the exports from the US to those countries accounted for approximately 0.4% of the total US exports (approximately $8 billion). According to Ferguson, those "do not seem like figures worth killing for"
Wikipedia has a good summary too.
Even before all the debunking started, I had to laugh through sections of the book as anyone with an Economics background knew he was writing bullshit.