http://www.useit.com/papers/anti-mac.html is a 1996 paper by Jakob Nielsen & Don Gentner that criticizes too-literal visual metaphors in the Macintosh user interface. Good read.
It's also interesting when metaphors don't change, failing to keep up with reality, e.g. the floppy disk being used a save metaphor, when floppy disks have not been prevalent for years.