The apartments are not in the centre of the city but are perfectly well-placed for several bus routes, and the trip into town is easy. The nearest Metro is about 10 minutes' walk.
Our first-floor apartment was modern, comfortable and clean with a plain but not unpleasant outside area to sit outside. There is air conditioning for the hotter months, and the AC units also functioned as effective heaters during our winter visit. The owner, Luis, was extremely helpful, and very receptive to a few small additions we recommended for the kitchen: he takes a great pride in the apartment, wants you to be comfortable and enjoy the flat but also Porto itself. He made several useful recommendations about places to eat and visit during our time in the city.
Next door, downstairs, there is an excellent bakery for breakfast bread and goodies, and they also do simple meals all day. There are a number of small shops and mini-markets nearby selling food - and all those things you simply forgot to bring.
One downside for anyone elderly or infirm is the parking. It isn't always easy to find somewhere nearby, and if you have a lot of baggage it could be very tiresome because stopping outside just isn't an option during busy periods of the day. Our flat was on the first floor (I believe there are two others under the same rental name on the floors above), and there is no lift. We are light sleepers but weren't troubled by traffic noise during the night.
We very much enjoyed our stay and as long as you don't mind the parking and being away from the city centre, I would thoroughly recommend it.