Sonja's place is located in the center of Valletta and you can reach public transfer (busses, ferries) easy and quick. Also, there are nice bars and restaurants at the corner and you can enjoy your nights and days exploring Valletta, without moving far away from the apartment. Probably everything interesting is at a reach in approx 10 minutes.
Consider that in summer the apartment gets warm, even if the windows are obscured the whole day. It is necessary to ventilate. In general, you will have a pleasant stay and don't miss anything.
The communication with our hosts was very fast and gentle.