Fantastic location. We were able to walk everywhere from the apartment and it's directly across the street from the bridge that connects to the other side of Porto. It's perfectly located but not too busy directly out front. As a bonus, there's a cute little bodega next door with old Mom and Pop owners. We bought wine, meat, and cheese from them, then walked across the street to the plaza for a sunset snack. Really great!
We were only 4, but the apt is more than large enough for a few more.
The only caveat of the apartment is the elevator is pretty loud - so if you're a late sleeper you'll certainly here it form inside the bedrooms. That being said, if you're ready to tackle the day in the morning, it wont bother you at all.