Most of the government on the earth are unitary. The unitary government is described as a centralized government. In which all the power is in the hand of a single agency. Like every other government, it has advantages and disadvantages. Unitary advantages are that it enforces and administrate through the country. Having greater unity and stability.
There would be fewer issues between national governments and local governments. It also has disadvantages, it is in how they operate. They have no business in local concerns, the responses are very slow on local issues. The United Kingdom is an example of a unitary government. Parliament has all the power in the U.K.
France is another country that has a unitary government. These authorities point out the direction for the central government but never do independently. Next is the federal government. This government is divided into two, one is the central government and the other is several local governments. The United States of America is an example for a Federal government. Both levels of government act directly on the people through their own sets of laws. The division of powers can be changed neither the local nor national level acting alone.
It has its own advantages. The advantages of the federal are that local government handle with local government and officials have to respond actively to the people that elect them. They also have more opportunities to participate in making important decisions that influence like government projects, fee, etc.
The disadvantages are the duplicate in services, the citizens living in the different area of the country will be treated differently like welfare, penalties, enforce laws. Last but not least is the Confederate government. It is an alliance of independent states. The Confederate government has power to only deal with issues that the member states have assigned to it. Articles of Confederation and the Confederate States of America are examples of a Confederate government. There are barely any Confederations in the world.
Like the Unitary and Federal it has advantages. It keeps power at small levels prevent the growth of large central government. Also disadvantages, without central government it is hard to enforce laws or collect taxes besides the lack of unity and common laws. All government has its own advantages and disadvantages.
And it depends on the people decide that which government is suited to them. A government can be given to local all the power or can be divided equally or have a strong central government. In the end, the aspect of good and bad ultimately up to the people think, want and feel which is needed which is not.