They are a fun lens! Glad you’re going to get one. I'm enjoying every chance to experiment with mine. I finally took mine out on its first field job last weekend. I was taking photos for an off road organization and one of the requests I got was to get everyone at the registration table. I did that with the regular lens but couldn't resist trying the fisheye. It was more of a test but included it with the rest in case they liked it. That photo is here:
http://nealrideout.zenfolio.com/p168532129/e223e2935
As you can see from the other photos people have shown in this thread, the fisheye can be used for fun or serious work. Let me know when you get one. Looking forward to seeing your shots.
Neal