Summary: this listing is for a dark basement with significant humidity issues albeit in a great location
The pros of the apartment are (1) the superb location and (2) the reactivity of the LovelyStay Team who manages the apartment.
The cons are the following:
(1) the apartment is basically an underground basement with no windows (just an access to a backdoor area, that is also on underground level) and suffers from a significant humidity issue. The bathroom area is made of a rock which absorbs humidity and affects the air quality of the apartment. Having stayed in the apartment for a week (using the dehumidifier and air conditioning provided by the owner) my partner and I had trouble sleeping and consistently woke up with chest pains and a cough because of the humidity. Our clothes were also damp and had a smell by the end of our stay.
(2) the garden and pool are not maintained. The garden did not look like the pictures in the listing and had trash spread throughout. The pool floor had a sort of green sludge covering it which made it not appealing at all. To illustrate, we did not use the pool a single time during our August stay.
(3) the description of the listing is misleading as it does not indicate that the apartment is in effect a basement with no windows, and that the apartment and garden are not connected. Rather, three flights of steep stairs separate the apartment from the garden area.
Overall, we were quite disappointed with this apartment and, despite the reactivity of the LovelyStay Team, we had no support from them or the owner when it came to addressing the humidity issue. I would not stay in this apartment again, although I would definitely come back to this street of Porto.