I went to Joseph's place with my mother and we were very happy there.
My mother really wanted a place with a good view of the harbor and this place was absolutely spectacular in that regard. The view out over the grand harbor from the balcony (accessible from one bedroom or the living room) is fantastic. We really loved watching the huge ships come in and out of the harbor as well as the various other harbor activities. The balcony is right next to the saluting battery too (visited by many precisely because of its great view). You can see the cannons which must be no more than 100 meters away and are at the same level as the balcony. More generally, the flat is very well situated for exploring the city of Valletta
The flat itself is large (lovely high ceilings), well furnished, well equipped, and a comfortable place to hang out and rest between excursions to the city and island. The beds are very comfortable and the showers were great too.
The hosts were also exceptionally accommodating. For example, our flight arrived at a time too late to eat out or buy food. So, the hosts kindly asked what we wanted and the food was waiting for us on arrival. Beyond that, all communication was clear and rapid.
Should we go back to Valletta, we wouldn't hesitate to stay there again.