We had a wonderful time at Pierre's apartment - the location is wonderful, just a few minutes walk from Mdina and public transport, in a very nice part of Rabat. Pierre and Denise were extremely accomodating even though we were arriving in Malta literally in the middle of the night, making arrangements for us to check in.
If you have trouble with stairs then this place might not be for you, but if you don't mind the workout, it's 100% worth it to see the views and relax on the balcony upstairs.
We would definitely stay here again, I highly recommend it.