I had a nice time in the apartment. As others also mentioned, it's a very basic 70s apartment (which in Portugal means - no central heating, and it can get a little chilly in there in winter even though there are electrical heaters), but the neighbourhood is calm and safe, shops are near, as well as the metro station, for me the WiFi was working all the time (sometimes a little slow, but it worked). Also the wooden floor is nice, and the kitchen is small but modern and has all you need to prepare small meals.
Communication and check-in was very professional. The flat was super clean. I'd come back when I'm coming to Porto again!