Point image formation at the center of the frame is good for a clear, sharp image. However, comet-like flare appears in places with lower image height due to the effects of inner coma. Inner coma is cancelled, though, as image height increases. What's more, a slight amount of astigmatism can be seen in the shape of the point formed. Resolution is relatively consistent from the center of the frame to the edges. Slightly more flare occurs with a rather low image height.
Rendering characteristics can be summarized as follows. Resolution is good and consistent from the center of the frame to the edges for sharp image formation. There is, however, a tendency for a slight amount of flare to occur in the center portions of the frame. Further, as points are clearly formed, rendering is more natural. Under-correction of spherical aberration and curvature of field results in beautiful background blur. Users can expect natural and pleasing blur characteristics.
Finally, let's look at some sample photos.