If you want to be in Valletta and swim in the Mediterranean, Rachel's flat is ideal. It's just a few metres from the entrance to the only beach in Valletta. I say beach, it's really a large slab of rock, but it's great—the sea is calm in the harbour area, there is Gino's cafe right there by the sea, it's not too crowded and not at all pretentious. It was a lovely place to spend the days. We visited the luxury infinity pool of a posh hotel where a friend was staying during our holiday, and decided we preferred "the slab." We also made a trip to Golden Bay, an impossibly picturesque sandy beach on the other side of Malta, but it was more crowded than the slab and the sea was choppier. The advantage of a rock beach is you don't get sand everywhere.
Rachel's flat is really two flats—an open plan basement flat, and a smaller version of the same just above on the ground floor. I travelled with a friend, and it was good for us to both have an individual space to ourselves. The beds were comfy, the kitchens and bathrooms well-equipped, and both flats had aircon (essential). There is a courtyard but it's internal to the building, and there is limited natural light indoors, so it was nice to go across the road and sit by the Siege Bell when lounging.
Valletta old town is small and you can walk it all very easily from the flat. There are plenty of nice bars and restaurants, and places you can pop out to for pastizzi in the morning. The city looks beautiful in every direction.
Rachel was very helpful and communicative. I would recommend her flat as a good base in a great location if you want the benefits of both the town and the sea on your doorstep.