Wow. Got this monster in last night. I've gotta say, it's really a piece of art. The focusing and zooming are incredibly smooth, and it appears very sharp through the range (although all I did were some "HEY GIRLFRIEND! *FLASH*" shots last night)
If you hold it near the back of the lens it's actually pretty well balanced on the camera. Although I don't see this being used a lot without some kind of tripod situation.
I'm excited to shoot some video with this thing.