Some pros of a bill of rights:
A bill of rights would give formal recognition to certain fundamental human rights.
A bill of rights would give further legal protection to certain minorities and the most vulnerable in our society.
A bill of rights would (in theory) protect society from rogue politicians and arbitrary government actions.
A bill of rights would serve as a minimum standard for the formation of laws and the administering of government policies.
A bill of rights would be an image booster for the country vis-à-vis the international community.
Some cons of a bill of rights:
A bill of rights would immediately and continually erode the sovereignty of the legislature.
A bill of rights would politicise the judiciary.
A bill of rights would be undemocratic, by giving unelected judges virtual executive powers and weakening the necessary checks and balances that are fundamental to good governance.