This is a fantastic place. I was lucky enough to spend a month at Flora's, and truly loved it. The flat is full of light, and you can even see the sun rising over the hills from the kitchen window. Every room is very spacious and cosy, and I loved how the welcoming minimalist style (and the little extra details like blackout blinds).
The location is great: just a few minutes from the metro station, and about a 30 minute walk from most places in the city centre. There are a few old buildings around, but having spent a month in the city this is characteristic of Porto. The area feels very safe, and the flat faces a private street, which is quiet at all times.
Flora (the host) was very welcoming and friendly, and truly wanted me to have a great stay. Success!