Namely friends of mine who fled Cuba during the 90s. From what I've heard from them and from my former students, this is what they dislike:
1) Until 1993, Cuba's relative crackdown on the Catholic Church (I say relative in comparison to the US, much less severe than in Soviet Europe).
2) Wages being extremely low, as in $7/day for people with high amounts of education (number based on what a co-worker told me she made as a chemistry teacher there). Yes, Cuba has had a very good education system compared to the rest of Latin America (with the possible exception of Colombia), but when there are tens of thousands of highly educated people working menial tasks, discontent is going to occur.
3) Perceived nepotism, particularly with Raul Castro.
4) The number of executions has been around the same as the US standard and maybe slightly higher over the past 20 years, but much of that is supressed information and the actual numbers are unknown. Estimated to be in the hundreds per year for a population that's over 11 million, compared to the 290 million or so that the US has.
5) Government's separation of Cubans from the tourists whenever possible. A friend (whose family fled Cuba when she was 9) told me that her son (who has the right to travel to Cuba due to family heritage) was not allowed to meet with his Cuban relatives at any of the resorts. Or to be more specific, his relatives could not visit any of the resorts as a guest of his.
Add all that up in addition to the usual complaints about a lack of official opposition parties and a faltering economy and you have quite a bit of discontent in Cuba.
Dylanfanatic
Illusions fall like the husk of a fruit, one after another, and the fruit is experience. - Narrator, Sylvie