We were the first tenants and spent nine nights there. We identified a couple of items to be fixed which were taken care of the next day.
The unit is on the street level of a narrow "close" which has foot traffic but no cars. The back of the unit is on an alley so there are windows on all rooms providing natural light. The building is stone the close is brick.
The unit was clean, well equipped, and adequately decorated. The bedroom is smallish but has a nice closet and chest of drawers. The living room is enough room to relax. The kitchen was great and has a washing machine for us longer term residents. The bath is more than adequate. A nice size for two people.
The location is great. It's 100 meters to a coffee shop, restaurants, groceries, and sundries. A block to the National Museum of Scotland.
It could be a bit noisy at night with nothing but stone, brick, and pavement around. That said, if you want the proximity and convenience of Old Town, I suspect that'll be true of any unit.
All things considered, we'd stay there again.