OK, so I also tried the “Strobella”, from http://www.strobella.com/:
The strap goes over your flash, so you shoot with it as a “shoot through”, between your flash and your subject.
This device is similar to a softbox, except it is going to throw light behind you too, so it will be good in a room with reflective white ceiling and walls. Or outdoors, where you have to shoot quickly and using direct light.
Results I got were similar to using other diffusers, but in the situations above, better than many. Here’s without, and then with, Strobella.
Nasty shadows and harsh look. Now we put the Strobella on:
As you can see, the shadows are much less harsh.
So when you are shooting something that you know will be bad (close up subjects where your flash is the predominant or only light), this works. It’ll save me regularly.
Drawbacks, other than the fact that you perhaps look a bit silly? It cuts one to two stops of light. Is it fairly cheaply made. It is small (the larger the light source, the softer the light).
Michael’s Quick Judgment: No panacea, and it will not last forever; but for the few Euros it costs, it’s not a bad thing to have one in your bag.