I fully agree with the ideas offered in post #2 and I would add that this book can be taken as a comment on the importance of an educated citizenry.
If the animals on the farm had all been educated, at least enough to read the commandments, they would have known that they were being manipulated. Maybe they could have done something to stop the dastardly pigs from ruining their bright future, their dream and their society.
As the time passes since the publication of this novel, it is still relevant and can still teach a moral lesson on politics and power. While it is certainly Orwell's commentary on Stalin and WWII, the moral of power and corruption is very much relevant today. The abuses of power, the caste system of society, and the struggles of the lower classes are all still themes in current society.
Knowing the historical relevance of the writing of this novel adds to the interest, but it does not demand it. The moral is evident without the background knowledge.