Karen is one of the best hosts I've ever met. She's really caring and ready to offer her help even in the middle of the night. When we arrived, she explained everything we need to know about the apartment and provided us with plenty of guidebooks as well as some snacks and soft drinks for the first day of our stay.
The apartment itself is very clean, quite spacious, and well-equipped. It has all you need, including a microwave and a washing machine. It's located in a quiet street so you won't be bothered by Valletta's nightlife. At the same time, it's rather close to the city center (max 10 min walk) and grocery stores. Be aware, though, that the apartment is rather dark as it's on the ground floor and tends to get very humid (Karen provides a dehumidifier, which is brilliant, but won't cover the entire flat). If you don't mind the humidity, though, I really recommend the place.