Mathias place is the best home you can stay in Porto.
The location is excellent: a classy neighborhood within walking distance to the Douro river and the charming streets along it with nice coffee shops and restaurants at fairly good prices
The apartment is perfect: extremely clean, well equipped, very nice beds to have good rest and the riverfront view is priceless with seating space to have a fine wining afternoon.
The host is very efficient: Mathias was a gentleman throughout the experience. Even before the agreement, he was very concern about details and he gave us excellent tips he also provides very useful advice written in detail.
Definitely the best place to stay in Porto!