Emma's apartment is in a great location, around 10 minutes' walk south of the castle and near various local grocery stores, which we appreciated! The apartment itself we found had plenty of room for the 6 of us, and was well stocked with towels, tea, coffee, shower essentials, etc. It is well maintained and was spotlessly clean - when we walked in my son (who is 11, and has experienced a few AirBnB locations) announced, "This is deluxe!" Emma is excellent at communication and she and her husband helped us with our specific needs when we raised them. The front door, as others have mentioned, takes some paying attention to in order to avoid it slamming! Overnight free parking on the street outside is achievable - there aren't many spaces but there always appears to be at least one. If not, the main street has parking on the same basis as Drumdryan Street.
Overall, this was a good choice for central Edinburgh and I wouldn't hesitate to try to book it again in a similar situation.