Viv and Paul's place is perfect for anyone coming to Edinburgh for the first time, as it's a short walking distance to so many key areas -- the backyard even has a great view of Edinburgh Castle! It's just a few minutes to the famed Victoria Street as well (yes, you'll see a constant stream of tourists taking photos!). You are also steps from a bunch of pubs, restaurants, cafes and food shopping options. Very easy and convenient.
The apartment is clean and has all the basics for cooking, and Viv and Paul leave plenty of supplies such as sheets, blankets and towels. There's also a guest guide with great suggestions for things to do and see. Viv is very responsive to any questions you have as well.
Be aware that the Grassmarket can get very busy over the weekends, and the pubs are absolutely hopping, so you may run into some loud merrymakers on the street. However, once you are inside the apartment, it's usually quiet. Overall, a great place to stay and get acquainted with the city!