We had the pleasure to stay at Vanessa's apartment during our one week stay in Lisbon. Vanessa was very friendly and helpful. She even had a very nice self made guide book of Lisbon and the surrounding sights!
The apartment was just as we expected. The house and the apartment are old, but decorated in a modern and fresh way. There are plenty of restaurants, cafes etc close to the apartment.
Alfama is a nice neighbourhood within a walking distance from the city center, bairro alto and other districts. Lisbon is a very lively city and Alfama is more quiet than eg Bairro Alto. However you can't avoid all the noises from the street (this didn't bother us).
We can highly recommend Vanessa and her apartment!