Sadly my copy's lens is softer than a week old banana. Lens hood helps a bit but not much.
I ended up with a barely-working copy that someone had totally mis-adjusted the lenses. I had the lenses moved to a working camera with abused lenses.
I now mostly contact print (platinum/palladium or carbon), so if the neg looks sharp on the light table with a loupe, I'm good to go. My present Rolleicord has the Xenar 75mm/3.5.
I did discover a weakness in the design on my last trip to Japan...but more of an operator-error reveled flaw. I was carrying the Rolliecord around on the tripod too much -- and that flexes the back of the camera causing small light leaks. I have a Rolliefix which addresses this issue, but it does not fit the older Rolliecords.
I can't remember if this was with my Flex (Planar 80mm/2.8) or the Cord...taken around 20 years ago...Platinum/palladium print