The flat makes a great base from which to explore Edinburgh. It's about a four minute walk from the Haymarket tram station, which is two stops from Princes Street, the closest to the Castle.
The flat itself was very comfortable, clean, and felt homely. Stuart, the host, kept in touch as necessary, and was quick to respond when we needed to ask anything.
It's not The Ritz, it then it's a damned site cheaper. It's a simple, comfortable flat, in a convenient location. We'd happily stay again.