Was talking to one of my nephews who is an architec and he said that building is crazy. The top floors are pressurized much like an ariplane because it is so high. He said the design can go gone much higher if desired. Architecs were worrried about money to build it. He also indicated the extra cost operating of a building this size are huge. (Pumping water to the top, elevators, etc.)
I'm looking forward to seeing a TV special on one of the "information" channels about how this was built and why certain things were done. I don't understand why you would need to pressurize the upper floors when they are "only" about 2,700 feet above sea level, which is barely half of what Denver is, for example. Would you ears pop that badly if you rode an express elevator to the top? Did they include a tuned mass damper to offset the wind loads? I can imagine the sway on the upper floors during high winds to be worse than a ship in rough water.
I'd be amazed if this building operates at anything but a huge loss for the foreseeable future. It's all about making a name for your city.