The main advantage of a shoe organizer made of fabric is that it generally costs less than one made of metal or plastic. Other than that, they do the same job: that of keeping shoes off your closet floor and/or shelves. Another advantage though, is that the cloth-pocket style of organizer is more versatile than its curved-wire counterpart. You can keep socks, jewelry, scarves, or whatever else will fit in the pockets.
Fabric shoe organizer:
Fabric shoe organizer pictured: Whitmor 6082-13 Natural Linen Soft Storage Over-the-Door Shoe Organizer
Another advantage of cloth is that it is gentle on the surface of your shoes – in other words, it won’t scratch them like metal or plastic could.