I lived there for two months and I enjoyed it very much. I would live there again.
Positive: The apartment is very pleasant. Small but practical. Lots of large windows. Good air conditioning. Comfortable bed. Tasteful art on the walls. Vera (on email) and Vasco (in person) are both very nice and helpful. The location is phenomenal. One block from the Principe Real square, surrounded by good restaurants, bars, and shops. A few steps to Bairro Alto, a focal point for nightlife. A short walk to Chiado, full of cafes and stores for everything.
Negative: If you want a quiet place, this isn't for you. It's an old building, so you hear every step your upstairs neighbors take. There are a couple of restaurants downstairs (one is literally under the apartment), and they play loud music at night (it stops at midnight). And the worst for me was the group of young men who congregate in front of the building every evening to drink beer on the street and talk and laugh so loud if feels they are inside the apartment. Some people won't be bothered by any of this, but it should be taken into account if you're looking for silence.
In balance, my experience there was very positive.