It doesn't get any better. My grandparents used them, my parents, and my wife and I now over the course of many years. There are some nice new ones out there, but if you can find a used one (flea market, etc.), I think the quality of the castings as well as the machining are better.
We have two--one with flanged lid and legs that was my dad's for outdoor use, and one for oven or stovetop use that was my mom's. Two of my buddies each have one, so when we get together we have four to work with. We've taken our boys camping a few times and done pot roasts that cannot be equaled cooking inside. What I like to do for the longer cooking times is start my fire about two hours ahead of time, and actually have two fires going. One fire is in the firepit for the cooking area. A second fire becomes a 'feeder fire', which is constantly producing coals. When the first fire burns down to coals you can begin cooking. The second fire will keep producing additional coals away from your immediate cooking area which you can shovel under and over the oven to replenish the coals that die out. The smoke flavor of oak or apple is unbelievable. The challenge is not with getting enough heat, but with not getting too much heat. We've been able to purchase some nice roasts, several inches thick. You can flour the meat, sear it on all sides in butter, add vegetables and spices to your liking, and reduce the heat. Let it roast for 2 1/2 or 3 hours and the meat will literally fall apart. It might be good to use a meat thermometer to double check. The flavor is unbelievable. We've also done pies, cakes, biscuits, and cobblers. The raspberry-pear cobbler is real good. . . . can't wait for some warmer weather!
Seasoning and cleaning the ovens can be a challenge. If you can season them outside you'll make everyone happier. You can use vegetable oil, and you're basically burning it onto the iron--that's why they end up black, it's a layer of carbon. You might want to repeat this a couple of times when your oven's new, but then you won't have to do it all that often. As far as cleaning, the best thing is hot water. It loosens most things you'll cook in the oven. I just add water when we're done cooking, bring it up to a hot temperature, then scrape everything out as much as possible. Let the water soften and loosen food that's stuck on. If you use a brillo or other aggressive pad you'll remove the seasoning. The green scratch pads seem to be okay, but go easy. On the odd occasion you might need to use a little soap. Some purists never use soap because it supposedly gets into the iron. Once you get used to using them, they open up a very enjoyable range of opportunities.