My family of 4 (hubby and sons 20y and 18y) and I stayed at Charlotte's place while vacationing. It is small but very clean and the accommodations were quite comfortable. We did a lot of sight seeing so the place was perfect. we made a hot breakfast in the morning, were out all day and came back to chill and then go to bed. Beds are European, low to the floor but really comfortable.
There is a cafe on the corner and a beautiful park across the street. The grocery store is a 15 min stroll, just on the other side of the park. You can walk to the Royal Mile in about 20 min. The neighborhood is residential, very quiet, and safe. The door to the apartment will lock when you leave out so be sure to have your keys. I wouldn't recommend the spot for people with really small children, the bathroom is nice but there isn't a tub to bathe little ones. Also, I would be nervous about little ones on the hall stairs. They are narrow and cement so they will need a hand hold going up and down. If you have a stroller, you will have to carry it up and down stairs, there isn't an elevator.
Overall it was a great location and if I visit Edinbrugh again, I'd want to stay here again.