What are the main criticisms of the Umayyad Caliphate?

Before Islam, the Umayyads comprised the main opposition group to the Prophet (saw) amongst the Meccans. They accepted Islam at the last moment when it became clear the Prophet (saw) was going to be victorious. Once they became a part of the Muslim community, they took advantage of circumstances, and, through political manipulation and machinations obtained power, displacing those with better claims based on their service to Islam, piety and closeness to the Prophet (saw). Some of the best-known critiques of their dynasty and rule appear in the works of the historians Jahiz in the ninth century in his "Risala fi Bani Umayya" and Maqrizi in the fifteenth century in his "Al-Niza wa al-takhasum fima bayna Bani Umayya wa-Bani Hashim" In power it is claimed they pursued policies which paid no regard to the requirements of Islam, often anti-Islamic. Some of the most prominent claims include: They oppressed and even caused the death of numerous men of religion and of the Prophet's family, most notably of the Prophet's grandson Hussain; They made the caliphate hereditary within the Umayyad family; They prevented non-Muslims from accepting Islam and obtaining the rights due to them; and They attacked the holy cities of Mecca and Medina, bombarding Mecca with catapults on two occasions. In sum, they ruled by force and tyranny.