How is the communism of the Cuba similar to Marx's ideas? How is it different from them?

Is Cuba a thriving society?

Are the failures of Cuba failures of communism itself or of something else? (or a mix?)

In the first place, it must be said that despite his immense intellectual contributions and his deep analysis of 19th century capitalism, Charles Marx didn't leave any book or writing outlining how a communist society would look like. He only wrote once that in communism, every person will go from receiving according to their capacity to receiving according to their needs. This is a very vague idea. So, is Cuba true to Marx? It's hard to say. Paramount leader Fidel Castro built a Communist Party and a communist state following the Soviet model. In orthodox Marxist practice, the government is the dictatorship of the proletariat, of the workers. What we have actually seen in Cuba is a dictatorship of Fidel Castro and his brother Raúl Castro, in which they and a small elite of top party, state and military officials hold power exclusively.

Prosperity in Cuba? Definitely no. The Cuban experiment is a failure after 60 years of communist rule; the Cuban economy is not dynamic, it is dominated by the higly ineffective state-run mammoths, many Cubans live in nearly-poverty, food rationing continues, it is tecnologically backward. No democratic freedoms. Most young people want to emigrate and settle in the US or elsewhere. The traditional Soviet-like economic model, a command economy, is a system that can't create wealth and can't lead to prosperity because its ideological foundations are wrong; only an economy based on a free-market and private enterprise can generate and sustain wealth. The American embargo is usually blamed by Cuban leader as the main reason for this situation, but Cuba can import technology from other countries, trade with them and get investments. So, why does it continue to lag behind?