My boyfriend and I slept at Marco's appartment for five nights and we had a wonderful stay.
The apartment is perfectly located in the center of the city and looks exactly like the pictures. Also it's very clean and offers everything needed (towels, hairdryer, oven etc.).
When we arrived our host gave us a map of the city and showed us places to visit and to go eat.
I highly recommend this apartment to anyone looking for a nice stay in Porto.