The Militaries have a reputation of being a little crankier/nippier than some of the other macaws, but that can vary greatly from individual bird to bird. The Military is my 2nd favorite Macaw (Greenwings #1 of course). The Most important thing to do is to NOT go into parrot ownership with false expectations and be ready for lots of work, bites, screaming, big messes, chewed on furniture - an the list goes on. No cuddles, kisses, no particularly liking you one little bit
The common intelligence is that a person should start with a little bird (cockatiel, parakeet) and get experience. Not me - you should get the parrot that you really want. With help from people on this forum and your own determination and intelligence, you can make it through the tough spots with any bird you get.