JFK was the last truly great president of the United States. He oversaw a country on the brink of nuclear war and dealt with several foreign policy crises. He inspired a nation to land on the moon within 10 years of his ascension to office. He also started the Peace Corps as a way to enhance America's foreign policy credentials with volunteer efforts. JFK wasn't perfect, but in terms of diplomacy and domestic programs, few could argue with his successes as he galvanized his own party into action during troubled times.
JFK set into motion important civil rights laws. He was a devoted public servant who cared about America. He was also a martyr. It is hard to attack JFK because he died serving his country. Although he made some mistakes in his personal life, he was a good president and a good leader.