I liked this flat and Sofia very much! The pictures are pretty accurate, it is bright, comfortable, quiet and well equipped. There is a good supermarket 'Fantastico' (фантастицо ) across the way with good quality selection of food, toiletries etc. The flat is on the 8th floor of a typical, slightly weathered, communist apartment block and has a nice view of Mount Vitosha, as in the picture.
Initially I did have trouble finding the building, arriving at Musagenitsa metro station at 10pm, I had a rough map however none of the streets or buildings seem to have streetsigns or numbers! I was wandering around in circles for nearly an hour before I heard somebody (turned out to be Vanessa's mum) shouting "Hello!". Maybe it's best to get a taxi or at least have a good map when you first arrive. Once you get your bearings however, it is an easy 5-10 minute walk to the Metro station. I didn't meet Vanessa, I was welcomed by Vanessa's mum and Vanessa's young daughter who were friendly and helpful.