Opinions/experience with Canon FD 500/8 mirror lenses?

Anybody able to tell of their experiences with these lenses? This is Canon, new FD, 500/8 reflex. Has drop in filters, built in tripod mount and hood.

I already own and am familiar with the shortcomings of reflex lenses in general, and am not interested in any comments about that.

I would like to know how this lens compares to other mirror lenses in general wrt to image quality.