The location of the flat is super for touristic aims: close to main attractions and the shopping street, there're plenty of cafes and restaurants nearby. Also there are 2 good supermarkets in the area, one is working everyday till 11 pm, which is great.
From there you can also reach both railway stations (São Bento, Campanhã) in about 20-25 mins by foot.
I think there may be too noisy in the summer: there's only a fan in the room and no A/C, so you will need to open windows. Anyway, we were there in february and it was very warm and calm there.
Marcelo was attentive and nice. Thanks a lot!