Very little noise insulation. Besides that, perfect.
Keep in mind, it's a historic place - so being on the first floor means you can hear your upstairs neighbours very well. Depending on the type of trip you have, this may get annoying.
We were there to sightsee, and only went back to the place to sleep. With earplugs, we had no problems. If you spend your time on their beautiful patio, you won't be bothered by any noise.
Ok, that aside, the location is amazing! We didn't know this, but the main bridge in porto has a top walkway, and bottom walkway. The house is less than 10min walk to the main church at the top! Which is perfect, because you get to start your day at the top (and only walk down), thou eventually you'll have to make the trek back up.
With a car, the building is the very first one when you get up the hill (don't miss the parking lot, because it's a one way street). Getting out is super easy as the road in front connects to the main street that takes you to the highway.
The house is old, but very well kept and clean. You have all the necessities, and lots of space : sitting room, entrance area, bathroom, kitchen, bedroom. O, and can't forget the patio with a beautiful view of the city.
The hosts were amazing - quick responses, personal check in, helpful suggestions and advice for your trip.