I never knew anybody who went to jail for speaking against the government neither directly heard such a story but I can believe that happens(journalist Yoanis Sanchez is an example). This is the way I see it, the government normally don't care much about this people or what they think/say, except when they try to do something that could affect their public image, for example if the Pope comes to visit and they want to organize a public protest. In this circunstances they are preventively sent to jail, and afterwards released when the visitor is gone. It is often the case that real criminals present themselves as "politic prisoners", that adds much noise to the whole situation and usually gets exaggerated by the media in Miami. While this is not ok, in Russia people actually get killed in similar circumstances, while the main opposition leaders in Cuba are all alive.
Cuban here, I also lived in Russia several months and my wife is Russian. Cuba is well below Russia (and of course North Corea) in terms of oppression. Marco Rubio never lived in Cuba and only reflects the feelings of the previous generation of Cuban that emigrated to Miami when Castro took the power. This is understandable as Castro took many of their properties but has nothing to do with how cubans from 2015 feel. This can be easily seen when you note that he spoke against the Cuba-US relationship improvement recently introduced by Obama which is clearly something most of cuban supported.