The location is wonderful. It faces the castle and is centrally located, with many restaurant, shopping and pub sites in the area. We were able to walk everywhere we wanted to visit within about 1.5 miles (FYI there are hills in Edinburgh so wear comfy shoes and clothes).
Douglas was very helpful coordinating our trip, had detailed instructions in the apartment and was pretty responsive. We had one issue come up (a faulty, noisy bathroom combination light/fan that was audible in the bedroom when it was switched on. We were also concerned it might burn out and cause a larger problem). This issue was not resolved during our 3 night stay, but this is not something that would at all deter us from staying here if we visit Edinburgh again.
Do yourself a favor and stay here when visiting Edinburgh!