I've been there as well, but was really disappointed that the "At the top" observation deck is barely more than halfway up. As a visitor you can't go anywhere near the actual top floor.Burj Khalifa baby, went to Dubai on deployment in 2013 and you know we all went to stand in line to go to the observation deck.
Have also been to Sears Tower and stood in those glass box things that jet out the side of the building.