My friends and I had a very pleasant stay in Porto. We were welcomed by Susana, who was very hospitable to us. If there was anything we needed to know, we could easily reach her (or the owner, Antoine). The bottle of Port wine on the table was a welcome surprise, fitting the surprising character of the city.
The apartment is located very well. The balcony/veranda is a good place to relax and have a glimpse at the Douro river. The apartment has enough space for 3-4 guests, maybe more. Supermarket, train station, nightlife are all in the vicinity. Would recommend to others, as it's definitely worth the price.