Customers most agreed on the following attributes:
I use it for snapshots/family photographs to lessen shadows and harshness. It works well for this purpose.
Everything is good about the diffuser, when it comes to diffusing the flash. It was made to do its job. Now if I could just keep the thing on there, it would be great. There is no locking device on it, so it keeps slipping off, with the slightest touch.
Slips on easily and attaches only as a friction fit. That is also the issue, after a little use, it easily wiggles off and falls off the SB-600 flash in the middle of use. Given the cost, I consider this product a very poor value. It could be a good value if re-engineered for reliable attachment.
This flash didn't come with any instructions so I just had to test which side was top and bottom as it doesn't tell you. Once its on, it fits snug and even though it's a bit bulky, I found that to be helpful when grabbing the flash to change its angle. The diffuser dome doesn't come off easy and snaps back on tight. I dropped it once with my flash and fortunately both came out fine. The diffuser dome came off but no damage had happened at all. It does a nice job of softening the light for portraits especially.
Fits firmly on flash head, does a nice job of difusing the flash, but is a little bulky.
I also have a Nikon SB-800 that came with a stock diffuser. I have found that I like this diffuser for the SB-800 better than the stock one.