I added two large diffusers to my set-up. Now I can use it for portraits. It won't work under strong sunlight, so no chance to overpower the sun with it, but I can imagine that it can be useful for outside evening events or dim halls with not proper ceiling (either strange colored or to large rooms with far away ceiling):
Overall I'm happy with the results and in my opinion it could be a good solution for photographers working outside without walls and ceilings. Wedding or event photographers could use it and it surely would attract the attention of the people.
A similar product is available on the market, the Bounce-Wall, by California Sunbounce. It's a bounce panel on a bracket reflecting the camera flash, which imitates flashlight bounced from a wall or ceiling. A review of it you can find on strobist:
The obvious advantage of my solution is that I have two light sources with more flexibility to adjust and modify.