Firstly strictly speaking there is no visible medium as the system uses air. This saves immensely on the labor, which is associated with conventional Hydroponic systems. It is also cleaner, with very little, if any, waste to dispose of, making it more environmentally friendly. This has the added benefit of a very low risk of bacterial problems that are usually associated with other growing mediums.
Secondly, the plants are always in contact with the air or their growing medium and will always receive sufficient oxygen for maximum growth. This, however, is not always the case with other types of growing medium, which may need changing frequently etc to grow properly.