More stay notes:
The air is as dusty and new construction smell bad as Four Seasons Seoul was when they opened and they don't have LG air purifiers either. I don't think it would help very much.
Like at FS, had to check out because sinuses couldn't take it anymore.
From my limited experience, they went for the dark grey marble and aged bronze for the bathroom fixtures. It was a terrible choice because the bathroom is already dark since there are no windows. When you turn on the water and dust comes up on the tub surface - you know it's time to go.
The executive lounge was better than Grand Hyatt, Signiel but not better than Shilla or Four Seasons. Still had a strong dusty feel in there.