...Its too quiet!
QUOTE
Weary Emirates Airbus A380 pilots are complaining that they cannot sleep in their crew-rest area in the aft main cabin because the aircraft is too quiet. The pilots say that the lack of engine noise in the A380's cabin compared with other long-haul airliners means they are constantly disturbed by sounds created by passengers, such as crying babies.[/quote]
More Here
More Here
Unbeliveable .. a problem ! ... maybe someone should TELL em to WAKE UP ! 
Its true though, even from the outside- the first thing that the guys down at NZAA told me when I asked what they thought of it was, it's too quiet for a machine of it's size!