My wife and I stayed here for 6 nights with our 7-year-old daughter. It's a lovely apartment and is perfectly located in central Porto. Despite its central location, it is quiet and peaceful, and there is a lovely outside private area.
The apartment was a good size for the three of us - it might feel a bit crowded with 4 adults, but fine as a base. The kitchen is decently equipped for some basic cooking, but there must be 100 eateries within a 200m radius, so you won't be short of food options.
We had a lovely stay and really enjoyed the experience.