João's place is a lovely old townhouse in a great location near the Bolhão Market and Trindade station (easy metro connections to both rail stations and the airport). There are many good inexpensive (local) restaurants nearby as this is not the main tourist area, yet it is walking distance to all of the historic centre.
The weather was unseasonably chilly for Porto in March and the townhouse heat struggled to cope with it, but I imagine it would be nice and airy during the more typical hot weather there.