Paul's apartment is a great location right by the entrance to the castle. We did have an issue where the shower broke early on in our stay which was unfortunately not fixed. Paul did arrange a partial refund for us which was appreciated.
The only other issue we found (not with Paul's place) was parking in Edinburgh in general seems hard to come by! We managed to find a good overnight car park called Princes Exchange which was about a 10 minute walk away.
Overall a nice stay in Edinburgh :)