Great location to be in easy walking distance of all the major tourist sites. Noise is not an issue when sleeping because the bedroom is tucked away at the back of the apartment. However, if you're working EST hours in the living room, then noise can be an issue because buskers set up on the street below the window every evening. The internet is usable for video calls but not great--I did lose a few words every hour (but no dropped calls).
The apartment is hosted by a rental company, so the service is not very personal, but replies were prompt. The toilet was leaking water onto the floor when we arrived, but the host got it fixed immediately. There is a turndown service on some days, which is a little confusing/strange (sometimes they come, sometimes they don't?). There was a strict limit on towels with a 20 euro charge for extra, which seemed unnecessarily harsh--especially with cleaning folks visiting every day.
Otherwise, the place is modern, tidy, and as pictured. All in all, it met our needs, and the location was perfect for us, but we'd look for another option if we visit Porto again, especially if planning to work remotely.