^* I don't know the numbers, but I seriously doubt that two 777s combined are more efficient than one A380. It's not for every route, but on some routes it definitely makes sense.
Actually, Singapore Airlines (the A380's launch customer) has been keeping track of their fleet's performance, and the A380 actually has a better fuel-consumed-per-passenger than the 747 and the 777 (also operated by Singapore Airlines).
However, this doesn't mean that I like the plane. It's basically just a fat A340. It's ugly.
On top of that, it handles like a pig, it's difficult to taxi, you can't park it anywhere, and it's a nightmare to service (why airports hate it).
...but the biggest problem, by a mile, is that it's been nothing more than a financial disaster for Airbus. As of November 2009, there are only 202 orders for the A380. It is estimated that as a result of the delays the A380 project hit after 2005, Airbus needs at least 400 orders, though some speculate nearly 500, for the project to break even (Airbus won't specify the actual number. Their last report put the number at around 350, but Airbus has stated that the number has risen).
I will give Airbus kudos for achieving what many thought was impossible. The A380 really is an engineering marvel.
...but it's still an ugly pig...
IMO, the 747 is still queen of the skies!
Handsome aircraft, isn't it?
Speaking of the A380, how's a picture of what was possibly the biggest inspiration for the A380 (never made it beyond the drawing board, though)?