Uranus tends to be more potent and more Uranian when retrograde. When Uranus is direct in the natal chart, intuitive and inventive impulses flow on a regular basis but, when it is retrograde, this energy builds to a certain level and then it explodes forth as in a "Eureka!" experience.
In this building-up process, Uranus tends to be more potent and more willfully dogmatic. Uranus' retrograde motion tends to stimulate deep psychological investigation and analysis. Its research, however, seeks answers that satisfies the mind and explains "Why?". This is frequently observed in people who have Uranus retrograde natally as they make mountains out of molehills in their quest to know WHY!
Obviously, this is an excellent time for mental studies that explore human behavior and psychology. It favors activities that require bursts of inventive and intuitive energy. It favors psychological counseling connected with freedom urges and disconnected patterns of relating.
When Uranus is retrograde natally, the rebellious urges tend to bottle up, bottle up and then burst forth seemingly out of nowhere. This stems from the fact that these people need to make changes internally before they can manifest them in the external world. During this "processing" phase, the individual rarely realizes just how rebellious he or she is.
When Uranus transits retrograde, it will reawaken freedom urges causing the individual to suddenly rebel against any ruts or confinement in the life. I feel that it is better to process what needs to change while Uranus is retrograde and actualize the change when it turns direct. The retrograde simply makes you aware but it is generally not wise to impulsively act upon an awareness.
source = http://www.lynnkoiner.com/astrology-articles/uranus-retrograde