Had a fantastic stay at Tom and Avril's flat in Haymarket. It's the best of both worlds--easy access to Edinburgh's central area together with the quietness of a residential area. Everything is spotless and exactly as shown in the pictures. There's a fully equipped kitchen, spacious living / dining room, and comfortable bedroom. Tom and Avril were welcoming hosts, and have clearly thought carefully about the needs of guests.
There are supermarkets, pubs, restaurants, and cafés nearby. The Co-op supermarket is literally at the top of the road and it's so easy to pop out to get ingredients to cook, or snacks. Haymarket station is nearby. The Castle, Royal Mile, Princes Street are 15-20mins walk away, or there are plenty of very efficient buses.
Overall, highly recommended.