The apartment looks really nice, in a renovated, clean and safe building. The location is awesome, right in the city center. The kitchen is well-equipped and the wifi is stable and fast (about 50-60 Mbps).
However, when we checked in we immediately noticed the guests before us had been smoking. When I confirmed we had checked in (as requested by the host) I asked the host about it, but they just didn't reply.
Porto can get quite chilly in the winter, luckily the apartment had electric heaters. However, don't use them at the same time as the washing machine/oven, because the power will go off. I messaged the host about this on a Saturday night and they replied immediately to explain how to get the power back on.