I think that any self-respecting Marxist would find lots to comment on in the way in which Machiavelli talks about manipulation of the populace to ensure power. This finds so many parallels in the way that Marx wrote about how power remained concentrated in the hands of the elite and how that power was based on manipulation.
For someone hoping to be the leader of a Marxist society, The Prince certainly provides helpful advice for maintaining power and controlling humans' thoughts and actions. However, a savvy Marxist would most likely not admit that he is following the teachings of The Prince because the average person who follows Marxist philosophy would not be attracted to a leader who proposes "dog-eat-dog" rule. Thus, Marxism seems to play out realistically in a Machiavellian style, but it would be highly unusual for a Marxist leader to publicly promote the philosophy of The Prince.
This has indeed been an interesting discussion. I would suggest that most of the Marxist regimes that have actually existed in the twentieth century (and the few that presently survive) have used techniques we commonly think of as Machiavellian. This is especially true of such Marxist rulers as Stalin, Mao, Kim Il Sung, et al., not to mention many of the Marxist rulers of Eastern Europe. Apparently Ramond Aron argued for similarities between Marxism and Machiavellianism in an essay summarized in the link below. My own sense is that the two philosophies (at least as Machiavelli's ideas are commonly understood) have much in common, especially when Marxism is actually put into practice rather than simply treated as a theory.
This has been an interesting debate. Although number 3 makes some practical points, I am not sure Machiavelli and Marx really go hand in hand. Machiavelli's ruler does not necessarily have the people's best interests at heart, and is clearly superior than his people.
It's important to remember that Machiavelli is writing in a world not yet experiencing the economic and social changes that Marx witnessed in his own age. He didn't think in terms of social classes, not in the way that Marx did, anyway.
That said, in some ways, Marx did for market relations what Machiavelli did for political relations. They both understood them in their modern forms as being divorced completely from any notion of morality, and argued that their respective subjects could best be understood if examined rationally.
I do not agree with the previous answer. I would argue that Marxists would see The Prince as a valuable guidebook for a ruler. It is true that they would argue that class struggle is important, but Machiavelli's work could easily be seen as good advice for the ruler in a Marxist society.
Marxism argues that a society typically needs to have a vanguard party that will impose a dictatorship of the proletariat. The leader of such a party would surely need to act in ways similar to those that Machiavelli advocates. The leader would need to use all possible means to maintain control over the country as he moves it towards true communism.
Machiavelli's is a practical guide for the ruler, not a prescription for what the social and class structure of a society should look like. Marxists would be drawn to the practical advice for keeping control over a population.
This is an interesting question. The answer would depend on how you read Machiavelli's Prince. If you think that the Prince is a satire, then a supporter of Marxism may actually look favorably upon it, because the Prince shows the evils of power and class struggle in the worst possible light as rulers ruthlessly subject "workers" and even seek to overcome their neighboring cities. The reasoning is that the Prince shows the evils of a non-communistic framework is such an evil light that communism may be the only logical outcome.
If a person take the Prince as actually advice, then a supporter of Marxism would be appalled by what it states. It goes completely against the teachings of Marx and Engels. Marxism in a nut shell is about the class struggle of the working class and there is nothing of this in Machiavelli's work.