Pros: inexpensive, perfectly cooked food, increases iron content of food, easy care, durable, high conductivity.
Cons: requires some caution when handling. It is very heavy, and gets very hot.
Why own a cast-iron skillet.
There really is no reason not to have at least one cast iron skillet in your house, and once you have one, to use it daily. It makes the best pancakes, grilled cheese, cornbread, pan-seared steak, eggs, and, well, everything cooks better in cast iron. Use of a cast iron skillet also increases the iron content of the food you cook in it, making your hemoglobin happy and fulfilled.
Cleaning and seasoning
There is hardly any learning curve. Clean it with soap and water when you bring it home (if it is new) and season it. The concept behind seasoning a pan is heat to open up the pores of the material, and grease to fill those spaces. There might be a few different "recipes" for seasoning cast iron, but they work on that same basic principle - heat and grease. Grease it up - crisco, peanut oil, bacon drippings (saved in those little tin containers with the sieve on top, naturally) - it doesn't really matter what you use, as long as it is saturated. Unsaturated oils like olive oil have too low of a smoke point and can become rancid. Heat it in the oven, low heat moderate heat, whatever, but do it for a long time. Iron has a low specific heat but there is a lot of it, so plan on leaving it in there for a couple hours. Thereafter, use it often, and it will get shinier and more non-stick with time. Try not to use soap too much when cleaning it. Scraping and wiping with a paper towel is better, but a little dilute soap solution won't kill it if it is necessary. Some people even put them in the dishwasher. I don't, but it is not unheard of.
You can take the pan from the stove to the oven and back again, but it gets incredibly hot. This, of course, is an unavoidable consequence of being a skillet near a heat source, but if you are used to being able to pick up a hot skillet by its cool plastic handle, it is easy to forget the handle gets just as hot as the pan itself. It can burn your hand very badly. acid-containing foods, like tomato sauce, can de-season your pan a bit. IF it does, just throw it in the oven again, with the thin coating of lard, or fry some bacon or something. Better yet, fry some bacon on low in the oven.
To sum up
It is a skillet. It is made of iron. It will give you a workout using it. It is inexpensive. You will be able to pass it on to your grandkids. It gets better with age.