You will not find a better apartment or location in central edinburgh...guaranteed! :) Having worked for a major hotel chain, i've stayed in a fair number of places and this trumps the best of them...the fit and finish is top notch and the whole experience in booking the apartment with Alison is at the top level of customer service. You will not find better communication.
And the location? ON the royal mile, almost exactly half way between holyrood palace and edinburgh castle...you do the math! Do not pass this up! It truly is a little 'retreat' :)