My partner and I spent one week in Mafalda's apartment and would highly recommend it to anyone wanting a comfortable base to explore the city. Mafalda's apartment is lovely, it has all of the things you would need would need for even a long term stay and some thoughtful useful extras (like an umbrella and beach towels!). The apartment is located in one of the prettiest neighborhoods of the city, is handy to the metro to get right across the city, and if you are visiting in June there is a local festival. There is a great supermarket 5min walk away, and an awesome Bifana shop in the same square.
Handy tip: If you are arriving via metro to Martim Moniz, if you walk toward where people are waiting for the number 12 tram you will see there is an escalator that will take you up the hill close to the apartment (which saves you carrying your luggage up yourself).