Very good for low-light photograpy.
As compact as his Ai sibling, just a little less sharp at all the apertures.
For landscape is not the best lens out there, because the borders are very soft even stopped down (and if you compare it to a 40/2 Leica Summicron C as I did you will be shocked from the difference!)
My sample suffers by a little bit of de-centering too, I think because of the cheap plastic costruction (cheap compared to the all-metal Ai version).
Everyway for low-light and reportage the convenience of the autofocus, especially with the dim viewfinders of the most of the DX cameras, supercedes the little loss in sharpening, so I rated it the same grade of the Ai.
Rating: low light & reportage