I stayed in Diogo's apartment for a month and enjoyed it. The apartment is large, full of sunlight, and has a great outdoor space. The kitchen is well equipped, and you'll find many food stores nearby.
As the description says, the apartment is in a great location, too.
It's a quick walk to the river (no more than ten minutes) and, if you like walking, you can even walk to the beach (approximately 25 minutes). There are plenty of buses to quickly get around Porto, including the beach and the historic center (or to connect to the metro and trains). Diogo is a great host. He takes the time to walk you around the neighborhood to show you where the essential places are.
I recommend this place.