Carol was really nice, gave clear instructions on how to get to the apartment, and was flexible on arriving and departure time. She also had some recommendation on what to do while in Edinburgh.
The apartment has an excellent location, within walking distance to the castle and shopping streets. We didn't use the kitchen facilities but it seemed to have everything you needed, even a washing machine.
The beds were comfortable, but the sofa bed in the living room is just that, a sofa bed and not very comfortable (would be OK for kids I guess).
I would definitely recommend Carols apartment for 4 persons :D