The place itself is clean, comfortable and well maintained. The kitchen is small, but it has everything you need. A bit of noise was the only drawback for me - coming from the street (especially when you open the window) and neighbours.
It is good located - metro station is within the walking distance and supermarket and cafes are nearby. If you like walking, you can reach the historic centre of Porto in around 30 minutes.
I highly recommend this place to anyone visiting Porto!