We were in 8542 on the Magic last June. I cannot think of one time when we were bothered by outside noise. If there was a party on deck, we were there, not in our room. Even when we went back to our room while the party was still going on, we didn't hear anything. We never heard noises during the night either. It could be we were just so exhausted, we didn't hear anything. DD5 and DD7 took turns sleeping in the ceiling bed; neither ever woke up during the night (except the time when DW was going to Shutters and saw Cinderella in the attrium with no line; she came back and woke the girls up to go visit! This is one of our better pictures, girls in Princess PJ's with the princess.)
The room is fairly close to the center staircase and elevators, which made it very convenient to run back to the room from anywhere. The first couple of days, we took the elevator. As the week went on, we found ourselves taking the stairs. The exercise felt good after all the eating we were doing.
If anything was wrong in the room, it was the privacy curtain. It only went half way across the room. I am not sure if that is how they are supposed to be, but it seemed odd it didn't go all the way across. We never felt the need to close it all the way, so we didn't say anything as it was not a bother to us.
On our next cruise, we booked the room next door, 8540. I would not be concerned about noise.