Lisa's flat is perfectly located in a quiet block but only two blocks from the sea promenade with its lovely cafes and views. The Maltese bus system is excellent and easy, and there's a stop two blocks away. If you wish to tour Valletta, the walk to Sliema Ferries is about ten minutes (or a bus ride).
The apartment is well equipped: I was grateful for the hair dryer. Beds are very comfy (but lower in height than North Americans norms if you have dodgy knees), and having a washing machine in the unit was a big plus. There's a small, well-stocked food shop up the block, and Manouche bakery (yum) is half a block in the other direction.
I would definitely recommend Lisa's flat as a good base from which to explore Malta.