Haven't had a chance to try it much yet, but seems to do exactly what it claims. I am using it on an A330 and the flash on it is so harsh that it is borderline unusable. The Puffer fits nicely into the hotshoe and does a good job of diffusing the light, though it does cut down on the overall light output a noticeable amount. It's a small trade-off though to be able to actually use the flash. The item, as mentioned by other reviewers of the non-Sony model, does have a cheap, plasticy, flimsy feel for $20, but I can't say I've had any problems with it thus far.
Update:
Having used it more, I have noticed that it tends to reflect an annoying amount of light back towards me as I'm photographing, though I still wouldn't change my rating. The light has to go somewhere, and as mentioned if some of it has to come back towards me to make the flash usable, so be it.