Cast iron pots are heavy. They can rust. The dark black seasoning will not stand up to hours of simmering if the liquid is acidic, like tomato sauce or sauerkraut. And once the seasoning layer is broached, excess iron can leak out of the pot into your food, risking iron overload disease. Thermal conductivity is eight times lower than copper, which is why cast iron fry pans are notorious for hot spots. The surface is mildly non-stick, but requires a bit of oil or fat to reach its full potential. Cast iron can be cleaned, but not aggressively. And I never use my cast iron pots to cook caramel or make crepes or to scrape off a tasty "fond".
A much superior technology is a laminate of durable stainless over an inner copper heat spreading layer, and a second generation Teflon non-stick film bonded to the cooking surface. Eggs slide out with no added fats, and brown uniformly from edge to edge. Burned sugar pops off in an acrid sheet. Home fries crust perfectly and are nearly greaseless. The stainless never rusts and can be scrubbed aggressively. Not to mention lightweight.
But Teflon has one Achilles heel- above 400F or so, Teflon breaks down and releases a number of fluorinated organic compounds which are dangerous in small doses. The seasoning on a cast iron pot will also break down at high temps, and while the actual compounds have not been carefully tested for toxicity, they are likely to be no worse than a bit of barbecue smoke. Which is to say toxic, but only in high doses.
So I use my cast iron pots on the grill. Under the broiler. Over a fire. For deep frying and steak searing. And every once in a while, when things get out of control, the seasoning pops up or burns off. But the pan is just as easily repaired, and soon as good as new.
This is why I took the time to develop a particularly effective seasoning technique. But to understand how this method works, a bit of background on non-stick surfaces is in order.