Pros: Durable, even heat, does things you can't do in an indoor kitchen
Cons: Heavy, Don't clean it with soap
The cast iron gains and retains heat well from coals spread above (on the lid) and below (under the oven) easily. I typically have two beds of coals going so that when one starts to die down underneath the oven, I just move the oven on top of the other bed of coals and stack fresh charcoal to replenish the used bed.
Depending on what you cook, you can feed 8-12 people with this large 8 qt. dutch oven. If you cook a one-pot meal, you only have to clean the oven itself, the lid and whatever other tools you use to cook (tongs, spatula, etc.) when you're finished. That's a huge plus when you're outside with limited light, limited water sources and want to make things less complicated (no need for soap).
If you typically cook for 4-6 (8 max), I'd look at the 6 quart oven - a more standard size. If you tend to cook one-pot meals for larger groups though, I'd definitely get the 8 quart.