If you've been cooking over a campfire or on a camp stove for a while, you've probably heard of (and perhaps have first-hand knowledge of) the superiority of cast iron. Cast iron heats evenly and holds heat very well, making it a superior cooking material in the Dutch oven department. Because you can cook at low temperatures and because it holds heat so well, it's a lot more forgiving for things like cooking over a campfire or even on a camp stove. What about the aluminum Dutch oven, though? Is this as good as a cast-iron Dutch oven?
Pros and cons
While the cast-iron Dutch oven is a superior cooking device, it's also about three times heavier than the aluminum Dutch oven. Although this may not be much of a problem for short hikes (or if you're not backpacking), that consideration goes out the window if you are hiking for long distances. In that case, an aluminum Dutch oven beats cast-iron because it's so much lighter, and will do the job just fine.
Cooking with an aluminum Dutch oven versus cast-iron
If you haven't cooked with an aluminum Dutch oven before, give yourself some practice before you take it out on the trail. Aluminum is much, much less forgiving when it comes to cooking, because it doesn't transfer heat as well and doesn't hold it as well, either. Therefore, the aluminum Dutch oven is much more "finicky," and is going to require a lot more finesse than a cast-iron Dutch oven will. Give yourself some time to learn how to cook with an aluminum Dutch of before you try cooking with it out in the boonies.
What about aluminum in your diet?
You may be one of those people who avoids cooking with anything aluminum-based, simply because radical science has found aluminum deposits in the brains of Alzheimer's patients; as the thinking goes, aluminum in the diet may contribute to or even cause these aluminum deposits and therefore may be a factor in whether or not you develop Alzheimer's disease.
In truth, whether or not those aluminum deposits come from aluminum cookware is debatable, although it may be a good idea to avoid it whenever you can. In this case, it's generally true that taking a "moderate" attitude is key. You may not be able to entirely avoid using aluminum cookware on the trail, for example, but you can certainly use cast-iron and other generally more acceptable materials in your cookware off the trail. But the bottom line is, it's up to you. You'll need to "weigh" whether or not the weight of cast iron (and its fragility relative to aluminum) is doable, or whether you can put up with an aluminum Dutch oven and other cooking devices for the short term.
You can also decide to buy an aluminum Dutch oven specifically for backpacking, and then choose cast-iron cookware for more moderate camping trips, like those taken at established campgrounds. If you have to carry a Dutch oven with you everywhere you go, chances are you'll consider the aluminum Dutch oven superior no matter its shortcomings. At the same time, if most of your camping is done in environments where you can transport most gear by car, they cast-iron Dutch oven is probably a better choice versus the aluminum. Use both and choose the best Dutch oven material for each particular situation, and you'll come out ahead in the long run.