It would be naive to assume it's an earthly paradise, definitely. But, I've also talked to some friends involved in organic farming and the use of widespread pesticides, herbicides, GMO's and other "improvements" are not nearly as widespread there, if they exist at all.
A large part of that is likely due to the embargo and relative poverty...although that depends if you define poverty as the poisoning of your environment. Not every place is as pristine as a tourist beach in Varadero, but I will suggest most places are a heck of a lot closer to that than not!
I think one of the key things I noticed about Cuba was the absence of advertising. What a blessing...no manufactured demand, no gaudy screaming billboards jarring your peace of mind, or any of the social ills that come from ramming consumerism down peoples' throats forcibly. There's happiness that comes from material security, and then there's happiness that comes from sources other than that...Cubans have much more of the latter than we do.