Sylvia and Ricardo's place is 5 STARS! Great location, great amenities, comfortable beds. Check-in was easy with keys left in the lock box. The kitchen has everything necessary for cooking. The hosts always responded within minutes and as I was also looking at real estate on this trip, Ricardo gave me some great insight into the current real estate market.
Don't be deterred from staying in Nova Gaia. It is just across the river and an easy 20 minute scenic walk across a bridge to the historic center of Porto. The promenade along the Douro river on the Gaia side is just as interesting as the one on the Porto side. Prices are a third less in Gaia, so save your money and stay in Sylvia and Ricardo's place. I would definitely stay here again!