Yes, Guantanamo Bay detainees are treated with basic rights. They have sufficient necessities, such as food, water, and medical care, and are living on an island on top of it. Most American prisoners, especially those taken prisoner by other countries, are not so lucky. Although no detainment is perfect, they are treated adequately.
Over 10 years ago, subsequent to the 9/11 attacks, people were housed at Guantanamo Bay as "enemy combatants" with the accusation that they were potential terrorists. Because the United States claimed they had no legal jurisdiction they maintained that it was acceptable to permit incarceration, and a range of torture and mistreatment which would be clearly against the Geneva convention. There have been numerous reports and films demonstrating the subhuman treatment, yet the people are held because the United States is exercising the power that comes with having the biggest stick.