Like all good dictators, Castro started out defending the poor and downtrodden, but he went off the rail when he realized that absolute power was a good thing for him.  In the end, Cubans are still poor and downtrodden.  Yes they can read, but what is the point of learning how to read and write when all you can read is government approved propaganda and you can only write things that the government approves.  In the meantime, Castro lived a very nice life - reports have him stashing away millions (kind of like Arafat), enjoying over 22 luxury houses, high speed motorboats and the company of many young and beautiful women.  

Trudeau may have seen him as an kind uncle, but the Trudeau family never really interacted with real Cuban - the fact the Justin is blind to the disgust that many Canadians have towards Castro demonstrates that he lives in a very, very thick bubble.  And that will not work well for him in the future.