Marques is right. Get a multi-trip ticket and enjoy the whole system. Taxis are fine if you need one, but the transit system is excellent.

Marques - it is about 10 minutes walking casually. It is not far at all.

We used Taxi which was cheap in order to come back from Porto downtown and we walked to the downtown. From our later experience in Lisbon I'd highly recommend to use Uber instead of a regular Taxi as this was half the price of a Taxi and very convenient

We used the metro only once and the Maruqes stop was less than 10 minutes walk. walking downtown is a downhill and it takes about 15-20 minutes. there is a bus stopping close to the hotel too. Taxis are not expensive in Porto. You chose a most lovely hotel with fantastic breakfast

I am sorry but I never noticed a metro stop. We used buses on a couple of occasions, which was easy, but otherwise just enjoyed the opportunity to walk and take in the ambience of the city.

We did not see a metro stop, best take a taxi