I really enjoyed my stay at this unit. It is located right in the Center (where you want to be in Porto) in a residential area a block from the main railroad station Sao Bento (a must see) and very close to many restaurants and the river.
The unit is very honey, comfortable and clean. It had one full bathroom in the bedroom and a half bathroom in the living room. It is completely updated. The only thing that it's missing is A/C, however the temperature inside kept quite cool in late Sept (temp was around mid 50s F at night) so we were able to sleep. Because we had to keep the windows open, it got somewhat loud at night. You can hear music at night (which is not a problem at all) what is an issue are the seagull birds that are extremely loud around 5am and will wake you. The Host said they are installing new A/Cs soon and so this issue will be short lived. The bed is very hard and I didn't find it very comfortable. But overall it is a great place to stay.
We arrived earlier than expected and one of the hosts welcomed us and allowed us to leave our luggage in the unit while it was being cleaned. This was very much appreciated.
He gave us various suggestions on restaurants and Taxi cab drivers. Close by there is a great local restaurant called Amada inside the Hotel International that has excellent lunch for €5 and great dinner dishes. There is also a great breakfast buffet in the Paris Hotel for €8pp. There are various vegetarian restaurants and restaurants that you can order take out to eat at the apt. You have to cross the street and visit Nata Lisbon and try one of their Nata desserts - It is amazing! Also, walk to the river pass the bridge to the Ferreira Port Wine House for a tour (it is worth it).
Overall I would recommend this unit to a couple or a group of up to four people. It would be a 5* if it had A/C