Toss-up between the rokinon 12 and this lens as to which one is more fun to toss onto the camera and see what happens. Both lenses have this delightful tendency to surprise. In this case, walking behind the wife / kid / father in law, a quick snap. Focus locked in just fine, entire shot was about 3 seconds power on to power off. Got her as she paused to look back behind her, before she spotted me.
Finally found someone willing to sell this lens used, as its out of stock all over Sydney. As I'd hoped, someone was willing to get rid of it on the basis of it's slow focusing and noise for a cheap price (excellent!). This is the first shot taken with it.