The LightSphere, as well as all other 'tupperware' diffusers, is a very inefficient device. What it does is spreads the available light from the flash in all directions. Most of that light is lost into space unless there are nearby reflective surfaces (preferably white) such as walls and/or ceiling to reflect the light back toward the subject. If you use one of the 'tupperware' diffusers in a large venue (dance hall, for example) or outdoors, all that happens is that 90% of the light generated by the flash unit is lost and does no good for the image at all. The flash takes longer to recycle and batteries are drained faster than if all of the light from the flash is aimed toward the subject.
You must realize that the only thing that softens shadows from a light source is something that makes that light source appear to be significantly larger. The 'tupperware' diffusers do not present a light source to the subject that are significantly larger than a "naked" flash unit.
Reflectors which direct all of the light toward the subject, but which present an apparent source size that is much larger than the flash unit's lens, are far more useful in more situations than any of the 'tupperware' diffusers. I use a LumiQuest Promax System
kit with my Speedlite, as it has a variety of ways it can be used depending on the situation.