Overall, we really enjoyed this unit and would def stay here again!
It is just as depicted, and in a great location for getting around. You can easily walk across the bridge to Porto, or down the hill to the River Douro where wine caves, restaurants, boat tours, and the tram are located. There's a small market across the street, a fruit/veggie store just below the unit, and many bakeries nearby. There's a large grocery store 2 Metro stops into Gaia.
The unit is between 2 Metro stations, both a 1/2 block away. I don't recommend buying more than a day or 2 of transit passes, until you get your bearing, because so many things to do are so walkable. We hardly used the Porto pass, and wouldn't buy again.
You can hear street noise from the train, park, restaurants, etc. in the living room and 1 bedroom. It can be quite loud.
You can take the blue train or the red train to the beach. You can catch a Tuk Tuk across the street for city tour, this was cool. The hop on hop off buses stop in front of the unit. Though tempted, the bus tour reviews were universally bad, so, we didn't try it. You can catch the city bus to the fishing village for lunch or dinner (nothing is really open from 3-7:30pish). Uber is also convenient.