On film mine was decently sharp, and the little I've bothered to try it on digital it's seemed not bad. But I greatly disliked its ergonomics. The 35 mm.-only pseudo-macro, the variable aperture and varifocal zoom, the loose barrel, etc. It's nice and hefty, for sure, and a very handy FX range, but ugh, it's a clumsy and ugly cuss.
I may be prejudiced, because I bought mine used at the same time as the AIS 80-200 F4, using both originally on a Nikon F. The 80-200 was, and still is, exceptionally good in just about every way the other isn't. It always surprised me that two more or less complementary zooms should come from the same company at the same time and be so different.