9 out of 10 points and recommendedSharp enough at F1.8 and gets pretty good by F4, nice colors, light weight, very cheapa little stiff focus
This review pertains to a black nose F.Zuiko F1.8, Serial 16xxxxx, tested om E-PM1.reviewed February 25th, 2013 (purchased for $25)
The particular copy I got is much better than Nikkor 50mm F1.8 from around the same time. I tried both E series Nikon and the normal one and both were much worse wide open. Stepped down they are probably comparable.
I don't see much CA or distortion. Wide open there is a little bit of 'soap coating' that you often see in old lenses wide open. It is however nowhere near the Nikkors. There are some flares even from distant objects that could be troublesome.
In terms of sharpness at F1.8 I would say it is on par with the M4/3 14-42mm kit. At closed-down apertures it is a little better.
One minor flaw could that, at least in my copy, the focus is somewhat stiff. This is a little of a problem during shooting video.