Very convenient apartment, the location is fantastic - lots of great bars and restaurants in the area, easy walking distance to tourist areas!
Other positives: quick and easy communication with the hosts, and very clean.
To keep in mind: I found that the apartment can be noisy at night between people coming and going in the building, and construction works outside in the morning...
The apartment was also very warm with no fan or air-con, so this made it difficult to sleep in hot weather.
Good place to base yourself if you want somewhere convenient to explore Porto.