There are so many great things about staying in Trystan's flat--not least of which is the location. It's walking distance to most of the touristy things, like the Castle, the Royal Mile and Arthur's Seat, as well as good restaurants.
Their bar downstairs is great, and you get good discounts for being a guest. (Try the margaritas!) You get a little bit of noise at night, but it never kept me up, and I consider myself a light sleeper.
The room is indeed spacious and private and looks exactly like the photo. I was in town for a wedding and wasn't able to spend much time in the flat, but the kitchen and common area are great to lounge in. Trystan and his brother Andy were very responsive and kept the place spotless.
If I come back to Edinburgh, this place would be my first choice.