Best stay, best host ever!
Carlos' flat is very spacious, clean, cozy, safe and fully equipped, located in a tranquil neighborhood. A private parking lot is another merit! He offered us some good advice for traveling Porto and even generously gave us a Porto wine and chocolates to enjoy. You can reach almost every main attraction of Porto on foot from the flat. There is a taxi stand right across the street as well.
I think you will not be able to find better place to stay. I will definitely choose this flat when I visit Porto again and highly recommend you doing so.
:D