Overall we enjoyed our stay, Ronaldo was super responsive and very keen to help and react to any issue.
Pros:
very responsive host;
charming/chic apartment;
comfortable bed;
excellent location, just a few steps from the center of Valletta
Niggles:
very spotty wifi;
the apartment living and sleeping areas are pretty small, such that there's nowhere to unpack a suitcase (no chest of drawers in the bedroom, and the only hanging space is actually downstairs, ie not in the bedroom area) - we lived out of suitcases on the bathroom floor for the duration of our stay;
the heating really doesn't work very well - the upstairs gets hot and the downstairs is pretty cold. This is hard to fix because there's only one thermostat for the unit, so either the downstairs is OK and the upstairs bedroom is hot, or the bedroom is ok and the downstairs is cold. There are no windows to open upstairs - the bathroom windows are fixed shut;
and finally, local church bells ring quite early in the morning!