1st I'll start with that, Elisio is a nice host and excellent communicator. Although we had a quite significant delay due to the flight he was flexible to invent plan "B" for smooth check-in. It appears he always has a plan "B".
2nd - the apartment is very clean and quiet, with no noises to disturb you.
3rd - the location is just fantastic - in the middle of everything that must be seen in Porto. You will just be within walking distance from the majority of the places which should be seen. On top of that many good pubs are situated in less than 10 min walking distance.
So, this is what you need for your stay in Porto!