Well, advantage of GSO: -You allways see the same spot of earth Disadvantage: -you never see anything else of earth -also - quite far out, so is need a lot more fuel and heavier rockets than LEO So, it's usefull for Communication or TV, because the Satelite is allways "on the same spot" in the night sky. Is also used for weathersurveilance (Meteosat are all in GSO)