My companion and I spent an enjoyable 3 days at Casa das Virtudes (3rd floor flat). Ana was away but Samuel (who lives in the flat below) greeted us, as arranged, and was pleasant and helpful.
The flat was clean and quiet, the bed comfortable, the shower efficient and the kitchen was adequate.
The location is pretty convenient for visiting the historic centre, about 20 minutes walk from the main station and the riverside, but be prepared for energetic urban hill walking!
The immediate neighbourhood is great- traditional houses in cobbled streets with a scattering of new restaurants. The bar in the street behind the flat is a real "local" and ideal for enjoying a cheap beer while the sun goes down over the river Duoro.
The flat has an unusual layout, which I could not really understand from the website description and the photos, although we managed to sort it out by email.