Or family of three (mom, dad, 9yo daughter) stayed in the 1st (middle) floor apartment for four nights at the start of our three-week Britain holiday. The place was perfect, and we will definitely stay there again on future trips to London.
The location was great, just a short two-minute walk to the Belsize Park Tube stop, and several restaurants, grocery stores, cleaners, and other amenities. We spent a lot of time in Camden Town and other places off of the Northern Line, so getting around was a snap.
The defining characteristic about the apartment, however, is its size. It is immense! It is easily four to five times the size of typical London hotel rooms, with a large living/dining area, a fully equipped kitchen, a huge bathroom (with a shower in the *middle* of the room), and very big bedroom. I was in London earlier this year and stayed at a typical coffin-sized hotel room for twice the rate, without half of the benefits of the Black and White House.
Carol-Anne was very welcoming and warm, especially so to our daughter, and was quick to provide suggestions and offer help when requested. If you have a family, her property is the perfect place to stay, with its size and kitchen--we stocked up at the local market on croissants, yogurt, and juice, and had a quick and cheap breakfast before leaving each morning (tea already provided, of course).