Totally recommend this place and Dioulde as a host.
The location is great, quiet area near the Garden of the Crystal palace, where you could go in the morning for a coffee and breakfast at the terrace on the lake while admiring the parc and the peacocks; 5 min (walking distance) away from the Lelo library and 20 min (walking) from the most magical place in Porto: Cais da Ribera.
Moreover, we arrived after midnight, and had no problems with the check-in, Dioulde made it so easy for us. :)