Very nice place, close to Trindade metro station and all major attractions.
I have only use the metro/tram to go to the beach, the rest of the time I walked as Maria's place is situated very close to restaurants, bars, shopping area and the river Douro.
Maria herself was very warm when welcoming us and answered all our questions and also gave us lots of useful tips. Definitely coming back, Porto is a beutiful city.