http://www.cookingissues.com/2010/02/16/heavy-metal-the-science-of-cast-iron-cooking/
Pros:
non-stick surface
superior browning ability
good heat conduction
Cons:
More maintenance than a regular pan (seasoning, cleaning, etc)
Cannot go in dishwasher
Heavy
In general, they're an excellent trade-off, and I use them a lot.
Heat the oven to 300oF
Coat the pan with lard or bacon grease. Don't use a liquid vegetable oil because it will leave a sticky surface and the pan will not be properly seasoned.
Put the pan in the oven. In 15 minutes, remove the pan & pour out any excess grease. Place the pan back in the oven and bake for 2 hours.
Repeating this process several times is recommended as it will help create a stronger "seasoning" bond.
Also, when you put the pan into service, it is recommended to use it initially for foods high in fat, such as bacon or foods cooked with fat, because the grease from these foods will help strengthen the seasoning.
If the pan was not seasoned properly or a portion of the seasoning wore off and food sticks to the surface or there is rust, then it should be properly cleaned and re-seasoned.
Remove any food residue by cleaning the pan thoroughly with hot water and a scouring pad. I understand that heating the pan first to a temperature that is still safe to touch helps open the pores of the metal and makes it easier to clean.
Dry the pan immediately with dish towel or paper towel.
Season the pan as outlined above.