Fabulous location - absolutely ideal. Lovely and clean, really bright & light apartment. Great communication and lovely welcome, including good local map & tips of where to go. The little balcony is a lovely afternoon sun trap.
Lots of lovely bars and restaurants on the doorstep and a handy little supermarket just round the corner, and only a few minutes walk down to the waterfront. It's such a compact city, everything is within easy walking distance, including getting over the river to visit the port cellars (Taylor's audio tour & tasting is well worth every penny and the bit of a walk further up the hill).
Be prepared to climb a lot of stairs to the apartment - but given the hilliness of the city, it's something you have to be ready to do in Porto anyway.
Beautiful apartment - you won't be disappointed.