Location: excellent. You are right in the middle of it all and close to great things that you can walk to. That does also mean the busy street right out the windows is quite bustling and noisy so something to consider if you like to be a bit removed from tourist central. Apartment is a good size and is secure.
Construction: unfortunately there is currently a demolition/construction site immediately next to the apartment with jackhammering and noise starting early around 7.30am and going past 6pm despite Porto's by-laws. So if you like to sleep in or come back to rest during the hot, stifling afternoons, that's not possible.
Otherwise it's a decent place to stay in Porto but I think it's better to know what you're getting into ahead of time, which we didn't.