We have spent three lovely days with my dad at Viv and Paul's place. The apartment is really pretty, fresh and clean. Besides, it is really well-located, in the Grassmarket area and just beneath the castle.
Viv and Paul are charming and communication is very easy with them. The only drawback may be the size of the bathroom, which for my dad was not so easy to use.
But overall, we are happy to recommend Viv and Paul's place.