I stayed with 5 other friends at Carlos' lovely apartment in the center of Porto during a long weekend. The apartment couldn't be better located (you really are in the heart of everything), and is fresh, modern and very clean. The apartment is located on a busy street, so expect a bit of noise at night if you are a light sleeper, but nothing earplugs can't fix. Communication with Carlos was very easy as well. I highly recommend this place and would come back in a heartbeat if we travel to Porto again.