So, what's wrong with MARC? In the context in which it was created, nothing is wrong with it. After all, it has served the library community well for many years. Like a comfortable, rambling old house MARC has provided the structure the library community could not have lived without.
MARC is, after all, a very efficient structure for communicating library information. It is flexible enough to have allowed renovation after renovation, and it is robust enough to have survived for a very long time.
Still, the signs of age are beginning to show.