Can imagine long lines and delays...
that's a lot of people to get boarded OnTime.
Another problem is there are only a few select airports who can handle the huge Airbus. At San Francisco you can't have 2 of them at the same terminal (side by side) so airports are having to make accommodations. This also means a lot of people are going to require a jumper flight to get to there final designation.
The bottom line for the A380's success is the gallons per passenger cost. If they can beat 747s 57.7 gallons per passenger then they have a market that will work. The fuel burn rate is the answer.