Our stay in Lisbon was great, and this apartment helped us to feel like home.
A must do is to go to the Time Out market with a huge variety of high quality food. And is just a couple of blocks from the apartment.
Even if the location of the apartment is not exactly downtown (not too far either) the best way to move around is to catch 25E tramway just 2 blocks away. The short trip is an experience by itself. You should first buy the transport card in the subway and add several trips. Otherwise on board of the tramway it costs double.