Silvia was really nice to us and really quick to answer all of our questions. See also keeps a book of interesting things to do or see in Porto which was of great help.
Regarding the appartment it is quite nice and well situated so everything is accessible. It didn't lack any important accommodation.
The Wi-Fi was ok but not very fast and the location of the appartment makes it noisy so you better bring ear plugs ;-)
Aside from that everything went great!