Great place to stay in Sliema, the flat is spacious & we planned. It has all the necessary things: equipped kitchen (cooker, oven, kettle, microwave, fridge, toaster, washing machine, etc), clean bathroom, comfortable bed, good Internet connection, air conditioning, and TV.
Location is very convenient with the seaside, a lot of restaurants and shops nearby. The building is located on a quite, residential street. You can walk everywhere nearby on foot, and there's also a ferry to Valletta which runs every 15-30 mins throughout the day.
It can be somewhat hard to find a parking spot (probably as in the whole Sliema), but we always managed to find one, a street or two away, as we usually returned around 5-7 PM (rotation time around the city). Just remember don't be picky with parking spots, if you see one then grab it.
Paula was very nice and the communication was very good. We've got picked by the driver from the airport despite late time (our flight was to arrive about 11 PM, but had a further 2h delay).
There is hard to point any flaws here. If I had to point one thing that we would actually love: an espresso/coffee machine (nespresso or similar).