The other reviewers said it best -- Qua is a great day spa, with experienced therapists and unique amenities that mimic the caledarium, tepidarium and frigidarium of the Roman baths. Very cool concept and a relaxing, enjoyable execution. Although pricey, I felt the prices were entirely in line with the quality of the treatments, amenities and staff.
The only thing lacking were robes large enough to accommodate people of size. I am a size 22 and my husband wears a 3X and the spa did not have robes large enough for us. For larger guests, I would recommend bringing your own white robe.