Ornamental kale is a twofer--a plant that provides two benefits in one. However, I use it only as cheap winter color for some of the large pots in my garden. Since it is also edible, many folks like to use it as garnish, or prepare it the same way as regular kale or cabbage.
Ornamental kale is available as an annual every fall in local nurseries, so I purchased enough to fill three pots. Many gardeners use it as a border plant, and in some of our large resorts, it is planted en masse in very large beds, and outlined with mums. Last year, I saw it used a lot in common areas of shopping centers. I imagine it is used everywhere in this same way.
The only problem I have with it is it grows very fast once planted and becomes leggy, losing its appeal as it ages. If it gets too warm, it loses some of the color, thus defeating the reason for planting it. If that happens this year, I guess I'll eat it.