My family and I stayed in Caroline's place for 3 nights and really enjoyed the apartment. It was clean, spacious, and has a fully stocked kitchen. We had plenty of hot water and the internet connection is good.
Just be aware, as some people mentioned that it is a noisy street that stays busy until after midnight. But, on the other hand you can walk anywhere in town cause it's so central.
All in all we had a lovely stay in Edinburgh and in Caroline's flat.