This article is pretty good at explaining the inneficiencies of traditional marxist thought. Many socialists believed that countries would be able to jump one at a time from capitalism to socialism, even if the rest of the world did not.
http://www.pww.org/article/view/4276/1/186/Demoralization with and alienation from the socialist cause grew uncontrollably; one manifestation was the growth of an underground economy to satisfy the demand for consumer products. Support for abandoning socialist development grew. The consumerist orientation grew particularly strong in Hungary, Czechoslovakia, Poland, and the GDR, while in the USSR and other European countries the economic dislocations led to periodic shortages even of basic necessities and social services. The latter first became evident to me in the case of the Soviet Union in the mid-1970s when data on infant mortality (which had begun to rise) mysteriously vanished from its statistical yearbooks. During subsequent stays in the Soviet Union in the 1980s, I observed first-hand the shortage of meat products, for instance, and even items of clothing like socks and gloves, again stimulating the underground economy.
Some ask whether, if market forces come to dominate, this would not lead to periodic crises similar to those experienced in all capitalist countries. Possibly so, but probably less severe, since a socialist market economy is not completely unplanned. The state stimulates investments on the basis of its long-range goals of development. Considerable leverage is obtained through state control of the basic infrastructures, credit, and taxation policies. For example, the Chinese authorities have just warned auto manufacturers that the industry is threatened by possible overproduction and are enacting measures to curtail investments in this industry, such as raising the tax on the assembly of a car to equal the tax on production of the entire car. Moreover, speculative activities are greatly restricted, which is why the Asian financial crisis at the end of the 1990s did not hit China or Vietnam.