It's a very nice studio for a short stay, bigger than it seems in the pictures (at least to me). The apartment is a bit far from downtown (hence 4/5 stars) but the location is still very convenient : it's close to the subway station (4 different lines to take you downtown) and to a train station if you want to explore a bit more of Portugal. We didn't take much of the subway and preferred walking, but it's still ~30mins to reach most historical sites. It was fine for us though and the quiet neighborhood was convenient for evenings and nights, with a few nice restaurants nearby.
The kitchen is fully equipped, so it is easy to cook pretty much anything. There is nothing much more to stay about the flat's equipment, we had everything we needed and everything worked fine.
Carlos is a very nice and attentive host. When we had one technical issue he immediately responded and made sure it would be taken care of. He took the time to give us some advice and recommendations to discover Porto and even other towns nearby. He will certainly answer all your questions and make sure you are comfortable.