RIP doesn't seem appropriate for a guy who should have gotten the Ceaușescu treatment. Castro will have to hope his Maker is more merciful than he ever was. A reminder of who Fidel Castro really was seems in order. A good place to start is the Babalu Blog; there's plenty at the link.
Meanwhile, it's also worth remembering this photo, in which Castro's brother Raul blindfolding a man about to be murdered by one of his brother's firing squads:
I'm also certain you will see the name of the dictator Castro overthrew, Fulgencio Batista, thrown around as someone who was worse. Batista was a monster, yes, but a tyrant is a tyrant. Life in Cuba won't change appreciably until Raul Castro and his partners in tyranny are gone. I hope that day arrives soon.