Basically what this thing does is split the beam of flash that comes out of your speedlite in two which you can then either bounce straight off a nearby surface, or you can attach the 'wings' which give out two soft beams of light. The photos below show the unit firstly without the wings and then with the wings attached.
Here's a couple of example photos that local model, Hanna ( Model Mayhem ID 3002308 ) was good enough to assist me with. The first shot was with wings attached and the next two were shot using the 'wall bounce' where the wings off. This is where the light is bounced straight off the available surfaces such as walls and ceilings. So far, I think I prefer using it this way as it looks bit more punchy and the catch lights look a bit better too As with most speedlite modifiers, it will suck a fair amount of power out of the flash so you'll need to use around ETTL +1.5
This was shot with wings attached:
This was shot using the 'wall bounce' method:
And this was also done with the bounce method.. but obviously bounced off the floor and ceiling (concrete) as it was shot in portrait orientation:
For me, the jury is still out on this modifier. I want to do some more testing but I'm liking it so far. I still love using beauty dishes and softboxes but that's not always an option and that's where the Wing Light shines with it's portability and why it appealed to me. You can get very 'studio like' results very quickly with minimal set up. Other reviews have questions it's durability but it seems like a fairly well put together unit.
If you're interested in viewing extremely thorough videos on comparisons with the Wing Light and other popular speedlite modifiers, simply Google 'Wing Light Diffuser'
