We had a very good time at Margaridas Appartment.
It is near to everything you "have" to see in the old city. Walking distance is debatable just because of the hills, steps and all the up and down of Lisbon :-).
All in one, we loved it. Margaridas tips are good to be followed and give a very good orientation in everything that's important: Sightseeing, Food and Drinking, Trips to the ocean and Sintra, and some specialities as well (LX Factory).
Appartment is good sized, very clean and exactly as described, fully equipped for the 2 of us.
Margarida was very supportive during the whole trip, especially organizing a taxi for our leave late in the evening.
Next time we'll come to Lisbon, we are going to check the avalaibility as well.