The apartment looks even better than I expected. Very good quality for this price. Good localisation: close to the metro station, supermarket and city centre (15 minutes on foot). Kitchen is small and not so well equiped - you can easily do breakfast but with dinner you might have a problem.
And the biggest advantage is a host Elisio. He replied for text really fast and helped us when we had a problem (we locked a key inside the apartment...). He dealed with it alone and we could enjoy our stay in Porto without worries.
All in all I really recommend this place! :)