Me and my partner recently completed a month stay and had a great time.
The apartment is centrally located in a lovely part of the city filled with all the neccesities along with great restaurants/bars/cafes. Good transport links to get you around though you are close enough to all the major sights that walking is always an option.
Apartment is large and clean, the included weekly cleaning service was a great addition for our longer stay. For people looking to work remotely the internet was fast and reliable throughout our four weeks.
Miguel was a dream host always on hand to give us recommendations and answer any questions about Porto we had. He really went above and beyond throughout our stay and we will be staying here again in our next visit.