Helen and Amos' place was great for my stay in Edinburgh. It is in a quiet, residential neighborhood (with some nearby shops and restaurants). It is easily walkable to the city center through a nice park. It is also convenient to buses and Haymarket train station.
The place itself was clean and comfortable. I enjoyed (perhaps too much), the box of shortbread cookies left as a welcome. There will also be cereal, milk, coffee and other small necessities waiting for you. Note there is no kitchen as such but there is a kettle, microwave and small fridge so you can sort yourself out for breakfast.
Helen and Amos were very helpful and accommodating, smoothing some of the chaos of my work related trip. All in all a great place to stay and a good value.