For some objectivity, we could look at some stats. PPP adjusted GDP per capita is much lower than the US, but way better than China. Education is excellent [2] because they spend 10% of their budget on it. Life expectancy (~79, gasp!) is higher than the United States. All of this with a near total embargo from the next-door global economic super power.
Western record on human rights is equally bad. In Castro's time, the Vietnam war resulted in 1.3 million deaths. More recently, the invasion of Iraq has resulted in 125,000 non-combatant deaths. Western allies today like Saudi have the most egregious human rights records.
I hate communism, but even with unrestrained exaggeration, Castro isn't Hitler. Such a claim is either a result of media manipulation of history or a flawed history curriculum.
[1] http://www.pewglobal.org/2008/02/19/global-views-on-castro-a...
[2] https://novakdjokovicfoundation.org/education-system-of-cuba...