Location! Just a few steps to the Royal Mile, restaurants. Several minutes walk to Waverly and New Town. Very responsive hosts: questions were answered within minutes.
There are a few caveats though: it was not clear from the description and photos that the twin bed in the small bedroom is a trundle bed, and when it's rolled out there's virtually no floor space for anything else. The mattress in the main bedroom could be a bit stronger, but it's fine for a couple of nights.
The bigger problem for the winter season is that the bathroom does not have any heating. Basically, you need to keep the door open when not in use.
Overall, this is a great place to stay: excellent location, well equipped kitchen, renovated bathroom and enough space for a family of four.