Animal Farm can be considered a warning to anyone who still believes that Communism can work. This form of government is always going to fail for the simple reason that in the presence of total power, people can be corrupted. For example, Napoleon, who in Animal Farm, becomes consumed with his power and in fact behaves worse than the farmer.
Communism, Fascism, or any totalitarian dictatorships, are particularly dangerous in underdeveloped nations. More than likely the people, the mass majority of them being peasants or poor, will be exploited, and abused, just as they are today in what was once known as Burma. The poor people, suffering terribly after a cyclone devastated their country, are being held hostage by a military government that refused to allow the U.S. or other nations to help the ravaged country.
Once allowed in, the relief aid was held back from the starving, dying masses, only to be distributed with pasted on labels of Generals names so that they would get credit for helping the survivors. A government that goes this far to control through censorship and propaganda is a prime example of why Animal Farm is such an important work. George Orwell warns us that power corrupts totally and total power corrupts totally.
Power and authority are ripe for abuse. That is one warning we can take which seems to apply for all ages of human history, past, present and future.
If the animals had maintained a vigilant and critical watch over those who launched themselves into power maybe the life of the farm could have lived up to its utopian promise. The watch was not vigilant. Those in power, the pigs, exploited their citizens and abused their power, setting themselves above and outside the rule of law.
Animal Farm is a warning in several ways. The most immediate and sweeping way is that it warns readers about the unrecognized dangers of Soviet style Communism. Orwell was intimately familiar with socialist ideologies, and he knew how idealists were falling into the trap of believing the propaganda of the regime, and how false it was. Napoleon is like Stalin, and Snowball like Trotsky; this is a direct commentary on their attempts to manage history. More generally, it is a warning about the dangers involved in trying to create any sort of utopian society here on earth.