This is a great diffuser. If I were you though I'd really just use an old milk jug.
I actually tried this thing out and it worked great. LOL
i now use the flip-it and "the bounce tunnel" I stole this from Cory Parris. Its basically a snoot that you use to bounce your flash off of walls and ceilings for a dramatic directional lighting effect. Made it myself out of velcro tape and a 99 cent black plastic binder from staples. Have fun.
The best part about the flip it is that you can adjust the amount of fill needed. This makes it easy to get rid of all shadow cast while still providing a little bit of fill for the eyes. Just bounce it at the ceiling and direct a bit of light forward. Sweet product, I'd get it. I hear the ligthsphere is good, but not in all situations. Good luck.
I'm telling you go with "the jug"