Over time, copper develops a beautiful patina. Corks stuck in the lid handle act as an always-cool surface to pick it up, even when the lid itself would require an oven mitt.
Copper pans are loved for being quick to warm and for their extremely even distribution of heat. They are often specifically called for in candy-making and other heat-sensitive recipes, but copper is useful for almost all your cooking, since the increased control and evenness of temperature makes everything easier.
Although copper is one of the most expensive materials for pans, for those who love to cook copper pots and pans are worth the investment. They also aren't difficult to take care of, despite what many believe. Like cast iron, the key is to understand the material, why it works, and what its weaknesses are.