Fidel Castro was a dictator. He got his position by overthrowing a different dictator. This should be noted in the first instance as it is pivotal to analyzing his stance as moral figure in political struggles. The pertinent question after his death, in terms of pop culture and not politics, is: Was Castro a hero for the working class or a decadent absolutist?
Public perception of individuals shifts from age to age when more, or less, knowledge is in the public mind about someone; and it especially shifts according to the current social environment. When young American liberals look at Fidel Castro and his legacy they see free healthcare and education, not repression and fear. Castro looks good to this generation, as Cuba has two achievements that wealthy modern America lacks. To an older generation Castro is the evil dictator who conspired with the Soviet Union to threaten the United States. In 50 years Castro will probably be forgotten altogether, not infamous or successful enough to remain in the public consciousness.
Castro was another dictator, no better or worse than any dictator who has ruled in the past. The west venerates democracy, and anyone who shuns democracy is a heretic to the new secular Truth. Castro is having his moment as his legacy is being debated, but he is just another brutal man who will disappear into the folds of history.