We liked our stay very much. The flat is super clean, well equipped and provides everything you need. The little terrace is beautiful and a/c worked well.
The area is local and provides lovely authentic food and good bars to chill out. The night spots are all in walking distance as well as the sights of the city. Location is ideal to discover Porto by foot. If you want to sleep long in the morning you won't make Helena's flat your first choice as you can hear people entering and exiting the main door as well as the neighbors upstairs. Overall we enjoyed and would recommend it!