We had a fantastic stay in this apartment. It is in an old converted block with a wonderful wrought iron staircase overlooking a lovely square.
We got the E line metro from the airport to Trinidade station, about a 5 minute walk away and were met outside by Walter. Filomena showed us around and was extremely hospitable with lots of great recommendations of things to do and places to eat.
We ate the first night at Antunes restaurant which is about 2 minutes away. Great food and excellent value. O Buracao and BBGourmet are both close by and would recommend.
There is a lovely grocery shop outside of the apartment for fresh fruit and milk, yoghurt etc. There is a good bkery about 4 doors up on the right as you walk out and a good cafe next to that. Ask for um pingo which is like a macchiato or a noisette in France.
Porto is a lovely city to wonder around. There are some good suggestions on this Channel 4 programme too.
https://www.channel4.com/programmes/travel-man-48-hours-in/on-demand/66403-002