They can certainly be a pain in the ass to season, though cooking in them and properly cleaning, drying and oiling will eventually get them seasoned. There's also the oven method and the stove-top method, similar to wok and/or cast iron seasoning.
Advantages are that they will be naturally nonstick once seasoned properly, they are lighter than cast iron and they heat up and cool down much more quickly than cast iron.
They're much different than stainless lined pans, such as All-Clad, which are not nonstick.
They look cool once seasoned.
More on the De Buyer pans here.