Mario's flat is very lovely! My friend and I only needed a place to stay for the night and it was perfect. Although it looks like it might be quite far from the centre, it's actually completely walkable to the Royal Mile etc.
Mario, of course, made it very easy as well. He gave us all the necessary instructions to get into the flat, as well as a list things to do in Edinburgh.
All in all, I would definitely recommend his place, and would love to stay there again :)