Okay. I actually had a really good experience here. I love this hotel and in all honesty, I'd move in if they'd let me so I decided on a whim to make a spa appointment. I really enjoyed it and the fact that it is so small was actually nice, intimate and relaxing. Keep in mind that this isn't a full service spa so there are certain treatments that aren't available. I didn't mind because I am so utterly anal that I research things before I'll try them. Just know what to expect. If you want more than you see offered on their website, another spa will suit you better. FWIW, I also frequent The Nob Hill Spa and Burke Williams.
The one thing that took away from my enjoyment was the possibility that people in the building across the way were watching me as I was in the soaking tub on the roof. The soaking tub is a great concept but the whole thing made me paranoid so I didn't enjoy it as much as I should have!