I can highly recommend this apartment!! Stayed there for two nights, it was was exactly as described and very clean. Free coffee and fruits, wifi and TV, well equiped kitchen... Everything you need!
The apartment is perfectly situated to explore the city (only 15 min to the riverside, 5 min to the Metro and 2 min to the next grocery store).
Joana was very welcoming and let me check in early in the morning, she had already prepared everything by then. Her tips for restaurants etc were very helpful, too!
I would definitly come back here, if I should return to Porto someday! :)