Stayed with a colleague in Williams apartment for a conference held at Dynamic Earth, the location of the apartment was perfect for us. It was close to the venue, had a lot of nice restaurants around and the fudge shop right outside was a great place to get a tasty gift to bring home. We did not find the location noisy even though there was a big construction work going on behind the building.
The apartment was very clean, well equipped and had a lot of things we would not expect, you can tell that William really takes care of his place. I will look for this place first if I get to Edinburgh again.