Communism is probably one of the greatest ideas ever thought....but the human beast is a greedy one, therefore it will always fail. Communism is based on an authoritarian overseer(s) that maintain the working people as a machine...to better the "whole". The "Authority" always becomes corrupt because of greed, and the system fails when the masses realize they are slaves. The root of all evil is arrogance & greed.
On a tribal level it can work. Anything more than that and you're asking for pure, unadulterated tyranny. Communism might sound good in theory, but when applied it has time and time again proven to work only against the people in which it enslaves. Communism, like socialism, are tools of tyrants.
I've never met a serious intellectual that supports communism. Just kids that, to put it frankly, don't know shit about shit.
I think it's a great concept. Human nature is far too flawed to ever really work though, unfortunately.
Marx can only be accepted as an observer of the laissez-faire capitalistic system, he was great at that. He cannot, however, be accepted as a founder of a better system.