We stayed here for one night only before going to the Douro region. We arrived fairly late but after getting the metro from the airport (about 35mins) you come out of the Campo 24 Agosto metro station, the flat was literally 2mins away, great for heavy bags and so easy to get to from the airport, not to mention cheap!
It was easy to get in with a key code at the front door and keys in a box by the flat door. The place itself was modern, bright and clean. We literally slept there one night and left in the morning so we didn't get a chance to use the facilities really but everything looked nice and modern.
We arrived at about 9/10pm so wanted so went for a walk locally towards the centre of town. We found a great little bar with live music and craft beers-a-plenty. The bar was called Terraplana and was a cool little spot, not unlike a trendy bar you might find in London or Edinburgh (where we stay).
We'd highly recommend this as somewhere to stay if you're on a budget. Be mindful that you are staying with other poeple, we did get woken up by some guys staying in the other room at about 5am but it was a saturday night so we'll let them off!! It was also a little dissapointing that we didn't get any recommendtions for somewhere to eat as we came in pretty late and very hungry but again, it was a Saturday night.
Porto itself looked lovely and we are coming back in a few days to explore a bit more, can't wait!