That apartment is just lovely! Really, really clean, newly renovated in the cool old house, has everything you might need starting from hairdrayer and iron and ending with matching dishes :) Perfect for 1-2 persons. Rua de Santa Catarinha or Av dos Aliados is just 2 steps away and actually all of the main places are just within 5-10 min walking distance. If you don't want, you don't even need to leave the apartment because looking out from the window you already are in the middle of everything (but just staying only at "home" and not seeing the beautiful Porto would be stupid) :)
Alexanda is great host, really easy to communicate and she and her husband were so nice to let me do really late check-in since my flight arrived so late.
Someone said before it can be a bit noisy - I would say that personally it didn't bother me at all. During the night it is quiet and I started to hear the "noise" just around 10-11 in the morning when it's actually a perfect time to get up and go to discover the city. Which is awesome, as I already mentioned before :)
Overall - I just loved the place. It's a place you would like to stay longer, or forever :)