The 50 is the only AF lens I own.
Build quality is plasticy compared to old manual focus lenses. It is soft wide open throughout, but especially in the corners.
Improves from 4.0 on and is quite sharp from f4-8 where it shines.
Out of focus rendering is downright ugly, one of the worst bokehs I have ever seen. I rarely use it for that reason.
Please note that I can only compare this lens to others I own (Nikkor AI-S, Leica, Zeiss).
A great lens for the price when used f4-8.