The location of the apartment is unbeatable - steps from both the central train station as well as all of the restaurants/bars on the Royal Mile.
The major downside of the apartment was the noise and the cleanliness. As other reviewers posted, the noise in the back bedroom is quite loud at night as it faces a central alley and the window is single paned. We also had an issue with the cleanliness/smell of the apartment that wasn't remedied during our stay.