We stayed for a week in Tony's cozy apartement. The flat has pretty much all the facilities you need, the shared citchen and bathroom were clean and we really felt comfortable. I would say the flat is perfect for those who are planning to have a longer stay in Marsalforn. Tony is a great host. You can really tell he is trying to make your stay as pleasant as possible. Whenever we reached out to him, we would get a fast and friendly reply.
Just as a side note: the room we stayed in has no aircon, which was clearly indicated in the description - we just overread it when making the booking. That being said, although it can get quite hot in the flat (we stayed there in mid August), in the evening the sun does not shine directly on the flat, so we did surprisingly well with just the fan. If aircon is a must have for you, I would recommend booking the bigger room of the two which has aircon.
We can definitely recommend Tony's apartement.