Flash Diffuser, is it useful?

When taking picture and when the available light is not sufficient, we usually use flash, for example when it's indoor or inside the house. Some people also use flash diffuser to make the result more natural or look like in the studio.

One (or two) flash diffusers i ever tried is from Gary Fong, the lightsphere and whale-tale reporter. What's the difference? I cannot comment too much about the difference between not using diffuser, and using either of them. I'm only going to show you the result and you can have your opinion yourself ;).

Not using diffuser: here and here.

Whale-tail Reporter: here and here.

Lightsphere: here and here.

I'm not sure whether they were indeed the result taken using the diffuser, but I think I'm 80% sure. I didn't use the "Image comment" setting in my camera, which may be useful if I use certain setting/tools and the info cannot be included in the EXIF unless if I use the comment.

The cons of using diffuser at least: you have to bring it with you which may be troublesome sometimes (I personally never brought it outside the house).

Anyway, you can see the difference. Which one do you like? (the result, not the people ;) )