Claudia has been an excellent host for me and my girlfriend. She was very clear in the communications and helped us immediately when we couldn't find the right street straight away (don't worry, it's really easy). She welcomed us personally, with a glass of port and nice cakes. She also told us elaborately about the city and showed us some places where we could go to. Mind you, the location of the apartment is excellent, with a lot of great places in walking distance (don't forget the restaurant underneath!).
We really enjoyed the apartment. It was very clean and felt luxurious. It even looked better than on the pictures. The bathroom is excellent with a great shower.
I would definitely recommend you this apartment for your stay in Porto.