For us, a couple traveling for several weeks, this flat was the perfect location - very close to all the major attractions and situated in a lovely area with restaurants, bars, groceries - everything you need :) The wi-fi worked very well and we had no interruption in service at all.
I do wish we had opportunity to meet David in person as his gracious attention to helping prepare us for our stay was extremely thoughtful. We arrived to a very tidy apartment to find everything we needed for our three night stay. Not only had he left small bottles of red and white wines to welcome us, he also provided cereals, juice, milk, sodas, and instant coffees and teas! Salt, pepper and olive oil were terrific additions for travelers who did not wish to carry this additional weight but who like to prepare an occasional meal in the apartment :)
David also provided maps of the area and, for those of us not savvy in the workings of European washers and dryers and appliances, instruction manuals were provided :)
Do be aware that to get to this lovely, castle-view apartment, you must climb from the 3rd to the 6th floor as there is no lift.
I can't recommend this apartment highly enough. If and when we have occasion to return to Edinburgh, I hope that David will have availability for us to stay!