Joao's place is very well located, once you make the trek up the hill from the Trinidad Metro station. Having the station nearby is very convenient.
We also enjoyed having some shops and supermarkets nearby to buy groceries and everyday you are teased by the pastry shops that are right outside the apartment complex.
The checkin process was very efficient and the two people who came from the concierge service (Sonia and Alex) were very friendly and gave us some very helpful hints on places to see and good restaurants etc.
So, in general we enjoyed our stay at Joao's place and we loved Porto.
The apartment did have some negatives for us. It is very small for 4 people, and a couple of little things like: the lack of light in the lounge/dining area, you have to eat your meals almost in the dark. No handsoap. Even some simple towel hangers in the bathroom. With a bit more thought the place would be excellent.