You can not ask for a better location if you are in Edinburgh. Right on the Royal mile and the building is a part of compound that is a must see for the literary tours. Although a bit of a climb on stairs (if you have a strolle/pram/heavy loggage - but this was disclosed to us in advance so no worries), we found the apartment very clean and very much like what was described on the website. If you are here for couple of days, hard to find a better place to stay. We'll look it up again whenever we'll be back. Thanks again David and Amy!
Just a note: inside the lock box, the lever needs to be twisted to open the key compartment (as we were just pressing it down with no result until we figured it out)