This is the perfect location. Just a block from Royal Mile. Grassmarket is one of the best locations in the city. We liked Hula across the street for healthy tasty lunch. Restaurant under the flat looked really good but never made it there. Not too much partying or college crowd in the area. Fairly quiet at night.
View was great. Updated flat felt clean and well thought out. There is a couchbed and a fold away in addition to 2 beds. I recommend only 4 people (two beds) in this flat so you can still sit at a table. The place settings are for 4 people too. The beds are comfy but the couch bed was not so much because, well, its a couchbed and the floors are not that level.
Overall really nice place. Bath was updated and clean. There are 89 stairs to get to the flat. It was no problem for us but be warned. Also the key box is top left to the left of the door. There were over a dozen boxes and non were labeled.