The Burj Khalifa—currently the tallest building in the world and a landmark on the Dubai skyline—was lauded for its luxury apartments and deluxe amenities when it opened in 2010.

But the building has been a huge flop with investors, and real estate prices there have plummeted from highs of $2,450 per-square-foot to around $721 per-square foot, the Wall Street Journal's Tahani Karrar-Lewsley reports today.

Investors called the building "distressed" back in February, bringing to mind other super-ambitious real estate projects that have failed in the emirate in recent years.

The Burj, which has 903 residential apartments, opened at a tough time, as other luxury high-rises were launching in Dubai and as the global economy went into a tailspin. The building's heavy security, long elevator trips and high service fees have also been a turn-off for prospective buyers, Karrar-Lewsley writes.

Even so, the developer told the Journal that the building is more than 80 percent occupied. And an investment-sales consultant interviewed by the Journal said he was confident that prices at the Burj would eventually climb, "but no one can say when."