I have been using this lens since it became available. It is one of my favourite Pentax 67 lenses (the others are 4/45mm and 4/300mm ED). It is exceptionally sharp and very useful for close-up work. You can reach a magnification of 1:2.8 with this lens without accessories. I am actually using this lens for close-up work in my avatar picture.
My accomplice will entertain you nearby while I make a beeline for the 75mm AL. Nothing like a bit of sharing and caring!