We had a really wonderful stay in Sonia's and Pedro's apartment; it's very close to everything, all the major attractions in Porto are within walking distance.
The apartment is at the third floor of a very nice, historic, renovated building which sits right in a wonderful square where lots of bars, restaurants are.
All is very clean and tidy; myself and my family (we've 3 kids) found the apartment arrangement perfect (my kids slept in the beds upstairs).
Sonia and Pedro warmly welcomed us at our arrival; they were very kind in providing us with lots of suggestions, details about what to do in Porto.
In short ... really recommended !; should we come in Porto again in the future, we'll first ask availability of their apartment to Sonia and Pedro. Thank you very much, hope to see you again !