It seems to me that Marx had a lot of good ideas that are still valid. He just failed to recognize the necessity of markets. Without markets there is no way to determine value or demand. I can recall when the Soviet Union used to have a "five year plan" to produce more grain, and while they were doing that, the country would run out of steel or something.
          In China, however, they still insist they are following the principals of Marxism, but are allowing markets to take care of some of the problems.