Maria's place couldn't be in a better location in Porto, right in the middle of Ribeiro and within walking distance of everything centro. The views are spectacular (above the rooftops and across the Duoro) and being four floors up, no street noise. Also, a convenient lift/elevator. Maria is one of the nicest and friendliest Airbnb hosts I've ever met, very responsive and genuinely helpful. I couldn't rate her or this place higher.
The only minor things (very minor) is that the flat shares a wall with the elevator mechanism so you'll hear that occasional minor motor noise as it is used throughout the day, but rarely during sleeping hours. Also, being so high up, sometimes the local seabirds sometimes congregate near the windows and have arguments at odd hours.