I've stayed in this flat a number of times while working away from home. It is stylish, relaxing and spacious all in one - with high ceilings, huge sofas and a nice fireplace.
The flat is located about 10 minutes walk from Princes Street / Waverley Station, or there are a number of buses and a tram stop nearby. It is about 30 minutes walk to Hollyrood Palace / Arthurs Seat, and also to Leith so there is plenty to explore! There are also some lovely restaurants and food places nearby (The Manna House Bakery, Pomegranate and No, 11 are really good).
Robert is a great host, and is quick to respond to any messages or queries. I can't recommend this place enough.