What makes Daoism unique?
Daoism is an eastern philosophy that originated in the Era of Warring States period in China during the Zhou Dynasty.
One of the things that makes Daoism unique is that, unlike the other two philosophies born of out the chaos of the latter Zhou Dynasty, Confucianism and legalism, Daoism does not support a strong centralized government. In fact, it supports as little government interference as possible.
One of the central ideas in Daoism is that we are all part of a life force that exists in all things and is known as "the way." By creating political and structural boundaries, like the Confucian concepts of filial piety and the golden relationships or the harsh discipline/reward system of legalism, we are not letting "the way" take its course. This in turn creates suffering. Man is only unhappy because of man's laws, customs, and traditions that are contrary to the ways of nature. This was clearly a reaction against Confucianism, which sought to control the people and restore order by creating a strict social guideline, and legalism, which sought to consolidate power by elevating the power of the emperor over his people.
Another thing that makes Daoism unique is that it is more of a "way of life" than a ruling philosophy. In China, even today, it is possible to live with Daoist principles and still be Confucian. They are not mutually exclusive philosophies.
Daoism is also unique because it encourages its followers to reject formal learning, political laws, or social customs in order to rely on instincts and senses. No other philosophy from the classical period encouraged finding balance by rejecting civilization.