We had a very pleasant stay in 'le chien noir'.
It was a big and clean appartement close to the city centre. The roof terrace is great to spend the evening in the last rays of sun.
When we arrived at the airport in Porto, we had quite some troubles getting to the appartement due to an exceptional problem with the metro. (it 2min walking from a metro stop, so a great way to get there otherwise ;) )
Carlos was very communicative and he was always reachable. When we arrived he showed us great places to visit (for sightseeing, eating, etc.)
I would really recommend trying it out.
A solid 5/5 for us