Although the appartment is on a busy street, there is absolutely no street noise in the appartment itself. It is conveniently located within walking distance from supermarkets and restaurants. We parked our car in the garage under the Ibis hotel (EUR 8,50 p day, thanks for the tip Artur) which was a good three minute walk.
The appartment itself was absolutely fine, with a lot of room. Everything was spot on clean and brand new.
And for the transport through Porto, Uber was our biggest friend, as some of the streets can be steep, especially after a long walk.