This is an old practiced that dates back to the great depression. It's a really resourceful way to use space. You can actually grow more fruit vertically or upside down then you can in the ground. Another benefit is that many bugs have a harder time finding the plants. Flying insects are still problematic, but scales & aphids are drastically reduced. Its also easier to feed the roots because the plants are close to eye level where as in a raised garden bed or in traditional garden rows, you have to bend over and work the soil.
Just don't expect yields must bigger then conventional container pots. Nasa even did some experiments in space to see if vertical growing was feasible during long space flights. The results were an unanimous "maybe." The marketing by topsy turvy is brilliant, but really the results are identical to what you would get to planting in a traditional pot. Some people have said the stems are stronger because the plants have to grow upward, but growers who use LST training get the same or better results regardless if they use pots of grow directly in ground.
My opinion is that growing in a raised bed is easy and attractive. Growing in pots is easy and portable. Growing vertically or upside-down makes no difference when it comes to yield, but if you are pressed for space, hanging an upside plant can expand your growing area with almost no negative consequences.