Carlos's apartment is well-located; a 10-15 min walk from Campanhã station, 2 mins to Heroismo metro and 15 mins into the Porto old town. Getting around was really straightforward and it was the perfect base from which to explore the city.
The apartment was simple, but well-equipped, clean and stylish. There is a nearby Lidl and a lovely local bakery over the road, for breakfast or "um lanche". A pharmacy and other shops are also nearby.
I booked fairly last-minute and Carlos was brilliant at responding to my questions regarding checking-in. When I arrived at the apartment he was there to greet me and spent some time talking me through the local sights and amenities. Checking-out was also really straightforward.
I'd certainly recommend Carlos's apartment for a city break in Porto.