When we arrived, the owners were very friendly and helpful. They gave a lot of information about Porto, including a map. When we needed something, we could always call and they answered as fast as they could.
The apartment was clean and nice. It was also easy to go to the city center of Porto.
We stayed with 5 adults in the apartment and we found it just big enough. The bed in the bedroom was good but the 2 other beds (a sofa that you can turn into a bed) weren't unfortunately that good to sleep in.
If you don't need that much of 'sleep-comfort', than I would recommend this apartment for sure! :-)