The apartment was not huge but it managed to squeeze in plenty of storage space, a decent sized bedroom and a bathroom that didn't feel squeezy. There was a great heater that kept the place warm and the windows kept out any street noise. It was also close to supermarkets and a great little family restaurant 3 seconds across the. You could easily walk to all the attractions of Porto as well - we never used public transport.
All up, we were quite impressed with the quality of the apartment.