As of my last knowledge update in September 2021, "gravity control" does not refer to a recognized scientific concept or technology. Gravity control typically falls within the realm of science fiction and speculative theories rather than established principles of measurement and instrumentation. Gravity, as understood in modern physics, is a fundamental force described by Einstein's General Theory of Relativity and Newton's Law of Universal Gravitation. Manipulating or controlling gravity in the way often portrayed in science fiction is not currently feasible based on our current understanding of physics and technology.
If by "gravity control" you are referring to hypothetical technologies that manipulate gravitational fields, it's important to note that this concept lies in the realm of speculative and theoretical science, and it's not something that has been realized or thoroughly studied as of my last update. As such, discussing advantages and disadvantages of such technology would be speculative and based on conjecture rather than established science.
If there have been significant developments in this field since my last update, I recommend consulting more recent and reliable sources for accurate information. Please provide additional context or clarification if you are referring to a specific technology or concept that has emerged after September 2021.