Honestly one of the most stylish places we've stayed with Airbnb. It was spotlessly clean. I wouldn't hesitate to stay there again.
So for the specific details, it's on the fourth floor with no elevator so it is a bit of a shlep to get up to. The plus side is that you have a nice over view of the street below and Missy of the sound is fairly muffled. As this is the touristy part of town, there is perpetual bagpipe music drifting up from the street during the day but it is faint enough to not be a bother (if you are even home during the day). Very quiet at night.
One qwerk of the flat is that the bed is tucked into a "sleeping closet" (not sure how else to describe it) where there is a door which opens onto the bed and there are walls on each side of the bed. No space around the sides of the bed. We really liked the space as it is dark and cozy and we slept really well, but it does require one to climb in and if one person needs to get out in the middle of the night they may have to climb over the other to get to the door. Overall it's a great way to get the bed out of the way in a small flat. We really loved it, but I could see it being a problem for some people who aren't very limber or who may be more on the highly claustrophobic side. (Although honestly if you can handle the stairs, you are probably more than limber enough to climb in and out of this bed).
Overall we loved this flat and it's great location as well as Edinburgh as a whole. Great place!