I stayed for one week in the penthouse. It's really spacious with a huge terrace on the roof. In the kitchen you'll find everything you need except a coffee-machine (if you're addicted that might be a problem). The room is as clean as it can be for an old house. It is a little dark inside the room because the windows are at the floor-level. But that might be an advantage during the hot summer.
Floriana is a cute neighbourhood with small grocery shops just around the corner where you get everything you need and really short ways to Valletta (Bus-Terminus, Waterfront, City Gate are only 10-15min away).
Claire and Alan are very nice hosts that help you with everything and sometimes more than that. That's AirBNB at it's best!
If you're looking for a luxury designer appartment, you should go somewhere else. If you're looking for a unique and typical maltese place with really heartwarming and helpfull hosts I strongly recommend that place.