I definately recommend it.
The location is right in the historical part of the city, literally 5 minutes walk from any important thing to see or places to eat.
The apartment is simple, but has everything you need to be confortable and rest after long days of walking. It eventually gets chill in the night, but the host provides you a heather to feel better.
They are very kind, quick to response and communicate and at disposition for tips on the city and modification of time of check in and out.
If you want to go to Porto this is the place to stay.