Actually it's Leitz which borrowed the zoom designs from Minolta. Leitz did not have any zoom in their catalogue and they made an agreement with Minolta to borrow technology. All first generation zooms from Leitz are derived from Minolta designs as far as I know (it goes without saying that Leitz produces according to stricter quality parameters).
I use the 28-85 extensively as a general walk-around zoom. It fares very well in distortion control and overall high contrast and, for a zoom, flare control also. Sharpness is very high although obviously a fixed focal length can perform better. It really is a jewel and if you find a second-hand one I suggest you use it as a general walk-around zoom. I use it a lot for architectural subjects as well.