The apartment is very comfortable, and it's within walking distance to the old town. Having two bathrooms is a plus, if travelling with a larger group, or if more independence is needed.
The apartment would benefit from adding small details in order for guests to feel cozy. It is very cold in terms of ambience and atmosphere, and a few plants, even if they're plastic ones, warm lights and lamps, and basic utensils such as kitchen paper, kitchen cloths were added, would make the apartment cozier and enjoyable.
Cleanliness requires improvement, as the apartment wasn't in great condition as we expected. We had to clean bathroom floor and kitchen handles, as they had hand prints on them and around. It wasn't a mess, but it felt the apartment had been clean in a rush.
The day after our check-in, we required cleaning, and no one cleaned it, this was, maybe, due to being Sunday.
Overall, we had a good stay, but we lacked a personal touch, and the attention to detail. It felt like this is an apartment to make money out of it, without really thinking of guests well-being and their feeling of warmth and comfort.
I would look for alternatives in the event of returning to the beautiful city of Porto.