I didn't get to meet Diana, but the girl who welcomed us (Katya) was very friendly and nice.
This apartment is located in the heart of Porto, the location was perfect and the apartment was very comfortable and nice. the views or the river were awesome. I would recommend it mostly because of its prime location.
The only thing I didn't like very much was the sofa bed was not very comfortable to sleep in. So i would recommend it more for 2 people instead of 4. Other than that, everything else was great.