Very nice apartment in a central location. There are a couple of metro stations nearby. It is well equipped with everything you need for your stay, including a washing machine. There are two elevators and it is easy to get to the apartment even with a baby stroller. The only negative aspect is that it is not suitable for very hot days (which I believe are not very common in Porto anyway). It has a glass enclosed balcony that acts as a defacto heat insulator. This is probably good in the winter, but in the summer once the apartment gets hot it won't easily cool down (it doesn't have air conditioner). During our stay there was a low power table fan which was not enough for the hot days, which fortunately were only 2 out of the 10 days that we stayed there.
In summary this place is great except for very hot days. I'd be happy to return.