Once trained if you get a young enough one they make good pack animals. We used donkeys as pack animals in the Marine Corps. at the animal packing school up at Bridgeport. They are REALLY different than horses. If you stress them too much they will lock up and then it is pretty much game over for getting them to do anything until you get them to come down a bit and unlock which can take hours depending on how badly they got stressed or scared. They can pack a huge amount of weight relative to their size and can be really friendly if treated right. You need to keep anything smaller than them out of their pasture with a lot of them e.g. dogs, kids, calves etc. If you are going to use one to halter break something like a calf you do it in the calves pasture not the donkeys. They can be super territorial about their pasture space and some of them will try and kill anything smaller than them that comes into it, like your dog etc. They seem to be fine with colts, but other livestock and dogs especially not so much. Kind of the same deal as with mules, if you like your dogs staying alive, keep them out of the pasture.
Anything worth doing, is worth doing well.