Ask HN: Benefits of circular images with css?

One advantage of using CSS to make an otherwise rectangular (really, square) image appear circular is that the underlying images won't become obsolete if the visual design changes to shift away from circular images.

Another is that commonly used lossy image codecs perform poorly on sharp transitions, and block-based compressors perform especially poor on rounded corners, and often, with transparency.

Update: I was really looking more from a user perspective. Does using a circular shape appeal more to users verse a square shape?

The underlying image is still a rectangle, it is just being manipulated with css to make it more stylistically appealing.