High maintainance and loud compared to what? Compared to a hyacinth macaw my goffin's is a peach. Compared to a cockatiel, she might be considered high maintainance and loud.
Mine is a rehome. Her very first home was mediocre. Small cage, not much toys, she didn't learn to play well, is lukewarm on petting and plucks some. Her second home was excellent although she still is a little wierd compared to the goffin's stereotype. Mine can be noisy, but if I ignore her she gives up. She generally has about 10 minutes in the evening where she screams a lot. If she's having a noisy sort of day then she might scream on and off for a few hours. Its not like contant noise. Its like a couple minutes of all out screaming. Fly around and make trouble for 20 minutes, then a few minutes of screaming.
Mine is sneaky about getting into things. She has escaped from her cage and nearly caused a fire by chewing the electrical cord off my fan while it was plugged in and I wasn't home. She's taken some strips of wood off from around my kitchen sink. She's taken some keys off my key board and she's super fast when she does it too. If she finds a pen or any similar shaped object that she can fly away with and take apart she will. Mine is fully flighted and pure grace in the air so I refuse to clip her. If yours is clipped or over-preens to the point of destroying their flight feathers, you can keep track of the bird better and it will get into a little bit less trouble. Although goffin's are so pluck prone, I wouldn't clip them unless your seeing aggression problems. Cockatoos in general have an insatiable curiosity and tend not to stay put real well unless you set rules from the start. A good number of goffin's cockatoos pluck. Make sure you get a cage bigger than you think you'll need for the size of bird, give it more toys than you think you'll need for the size of bird. Go heavy on the foraging toys. Don't give it as much attention as she thinks she needs lest you turn her into a spoiled brat that makes every one crazy. Teach it to be a bird first, not your snuggle baby. They can be very good pets. Not as difficult as the larger 'toos, but they are still a cockatoo so the potential is always there for problems.
Mine is moody and sometimes prone to taking a swipe at my face. Like I said, nobody really cuddled her when she was young so I have to be careful what kind of mood she's in before I pet her. And if she is in a snuggly mood, I stop petting her periodically so she has a chance to move away from me rather than sitting there silently getting fed up with it and then lashing out and biting. She's a little strange. I find my sulfur easier to read. I think Cassie might be a little atypical compared to most G2s.