I don't know him personally so I can't tell you whether or not
he is, but from a pure political and historical perspective he is a
dictator and he did aim nuclear bombs at the U.S.; although, from a
historical perspective the U.S. has not always been good towards
Cuba either, both politically and economically, so to be fair I
think the best thing to say is that he is but mostly because he's a
dictator and that in itself is bad.
In fairness to Castro the US where threatening him and tried to
kill him on many occasions, so he had a reason for allowing the
Russians to aim nukes at the USA. Cuba is one of few countries
meeting the WWF sustainable development category. To sum it up,
Fidel Castro is taught to be a bad person in America because he
challenged their way of government and dared to overthrow a US
backed regime just as corrupt as the current one. America does not
support democracy, it supports capitalism.