We loved our stay at Vila Nova de Gaia! The location was beautiful, the neighborhood was quiet and the apartment was comfortable with everything you need.   I would say if you are older or handicapped this would not be a good choice unless you uber everywhere.
We walked everyday down a very long hill to the village and it is quite the hike back up. When we got down to the village we rented the e-scooters and headed towards the main village and the historical Porto. It was so fun!
I cooked two nights which was super enjoyable. Once you settle in there is no running out to grab something unless you uber out so make sure you have all the supplies you need if you want to cook in.
The main bedroom curtains are not very dark so luckily we traveled with our sleep masks. If you enjoy a dark room remember to bring one.
I loved the whole experience, the location and Porto. I would stay here again anytime.