We had a wonderful stay at Claudia's place in Porto. The location is perfect--right in the heart of the old downtown, surrounded by restaurants and all the major tourist attractions. The river is literally at the end of the street. Everyplace we wanted to go was within an easy 10 minute walk.
The apartment itself is beautiful and exactly as described, with stylish furnishings, good reliable wi-fi, and all the amenities you might need. (And if you're missing anything, there's a little market right across the street, which is super convenient--there are not a lot of markets, so having one so close is a plus.) As other reviewers have said, there is noise from the street, but that's because you are in a very vibrant neighborhood and people in Portugal love to be out socializing in the street in the evenings. (The best thing to do is to join them!) This would be the case no matter where you stayed in the tourist part of town. We were there in the middle of July and found the apartment to be cool and comfortable, with big windows to let in the breeze and heavy shutters if you want a nice dark room for sleeping.
Claudia was very helpful--she met us at the apartment, showed us around, gave us lots of good suggestions for where to go during our stay, and even arranged a taxi to the airport for us when I was worried about hailing a cab at 6 AM! So helpful to have a car waiting. Highly recommended in every way!