I've got a 90mm C lens, and it's pretty darned sharp. Back when I first got it, I took a full length portrait of a fellow of slightly above average height, leaving a bit of room at both the top and bottom of the frame. Under my 4X loupe, I could clearly read the writing embossed on the button holding up his jeans--it was absolutely sharp and defined.
I would be quite pleased to know my 35mm lenses are producing such resolution and definition on an equivalent area of film. Medium format lenses generally don't need nor boast resolution as high as lenses for smaller formats, as less magnification is required for the same print size. But my 90 seems to have just as high resolution as the top-of-the-line Nikon lenses I own. With that, I am absolutely satisfied.