We loved our stay at Jorge & Celeste's. The shower is incredible, the bed is comfy, the view is one of the best in the city. The kitchen has all the necessities that you might need. We have stayed in several Airbnb's in the Porto area. This is one of the best.
One note, we stayed in the Rivers apartment on the top floor. The stairs up to the apartment are quite steep. I would not recommend this location if you have mobility issues. But if you can handle the stairs, make this your choice for your visit to the Porto/Gaia area.
PS. Take advantage of the €25 electric bike rental that is available from CICLO that is offered by Jorge & Celeste. It is a great way to see the city. Riding up the hills is made incredibly easy with the e-bikes.