I have this cheap fisheye lens that I can screw onto my kit lens, and I wondered recently why I never used it. So I decided it must be experienced!
And I realized why I never use it, it's terrible. The image is completely soft anywhere but the center, and the chromatic aberrations have to be seen to be believed (I worked really hard in Lightroom to get rid of them here). All reasons I can't wait to get rid of it and potentially pick up the Lensbaby fisheye optic, hoping that it performs a little better.
Still, there's something to be said for even a failed experiment. And I do like the experience of shooting with a fisheye, even if coming home and reviewing the images from this one was a bit of a letdown. As I recall, I paid less than $40 for it, so I really can't complain.