Ana's apartment is a very handy and comfy place standing in the middle of Belem. I went there with my girlfriend and it suited us perfectly to get to know Lisbon. Although it is quite far from the city centre, parking is free in case you are driving your own car and the tram stop could not be closer, so transportation should not be an issue. If you are planning to party at nights I would book something closer to Lisbon.
Ana also left some food for breakfast for us (eggs, bread, ham, coffe, fruit...) which we deeply appreciatted! Wifi worked fine and air conditioning only in the living room.
Overall, I would definately recommend the place.