The apartment is wonderful. It is near the metro station (1 min walk) and you can take it to go to downtown or if you're more into doing some exercise you can also walk and explore the city to get to centro historico.
We found the apartment itself is very accommodating. Everything was clean, it was spacious and everything was organised.
Helena was available to respond very quickly if we needed something. And although our check in time was a bit late at night, Helena welcomed us enthusiastically, showed us everything about the apartment and explained a little bit about the city Porto itself.
Overall the experience was really great and we have no complaints! We wish to come back to Porto again and to stay at this apartment :)