Cast iron cookware is an extremely versatile and economic alternative to expensive copper and copper clad cookware. If you aren't currently using at least a couple of cast iron pans in your kitchen, you really should consider it.
Cast iron has several advantages over other cookware. Cast iron pans have excellent heat conduction and retention, so you get even heating over the whole surface of the pan. If there are no wooden handles on your cast iron cookware, you can use it either on the stove, or in the oven. Properly seasoned and cared for, cast iron is just as non stick as any fancy non-stick pans. Cast iron is very durable. Some of you may have cast iron pans from your grandmother's kitchen that are still in excellent condition. Cast iron pans are very inexpensive compared to the fancy copper pans.
On the other side of the coin, there are some disadvantages to cast iron. Cast iron pans are very heavy. If not properly treated, cast iron pans can be prone to rust. Cast iron pans must be hand washed, they are not dishwasher safe. Cast iron pans require a bit more maintenance than regular pans (but not too much more).
If you properly care for your cast iron, it will give you many years of use. Some cast iron comes pre-seasoned, so you don't need to season it yourself. If you need to season it, simply rub it with oil, shortening, or lard, and heat for an hour in a 300 degree oven. Then remove the pan and let it cool. You can repeat this process a couple more times to strengthen the bond of the seasoning. What seasoning does is it fills in the pores in the iron with the oil, helping to prevent food from sticking and to create a protective coating.
You should never use soap in a cast iron pan. To clean them, just use hot water and a plastic scouring pad, don't use steel wool, or it could ruin the seasoning (if this happens, just re-season the pan). After washing, dry the pan thoroughly with lint free paper towels. Store the pans with the lid off to prevent moisture from building up and causing the pan to rust.
Other cast iron care tips: Do not use cast iron to cook acidic foods, cast iron is a reactive metal, and will react with the acids. Never use your cast iron pans to store food; You can use them to keep food warm during a meal, but when the meal is over, move the food into proper storage containers, and wash your pan.
If you don't currently have any cast iron cookware, I suggest getting some and trying it. A good skillet and Dutch oven are good pans to start with. They can be used for pan frying, deep frying, roasting, and stewing. I've even used two pans as a makeshift sandwich press.
Whatever the disadvantages of cast iron cookware, they are far outweighed by the advantages. Properly cared for, cast iron cookware will last for years of great meals.