Location of this venue is excellent; right on the river front near to the hustle and bustle but far enough away to avoid crowds.
We found the flat to be quite uncomfortable - there is no Air Conditioning however a large fan is provided to regulate the temperature. The pillows were very poor - the best comparison I have would be the sort of pillow you get given on a long-haul economy flight, small foamy things with minimal support. We asked for additional pillows to be provided after the first night, and to be fair the hosts were prompt in responding positively.
Note that an Iron is not included by default; again we had to ask and we received a quick enough response. Never did get an ironing board though - although technically we didn't specify...
Hot water for the building is limited across each of the rooms - which I guess is down to the nature of the area and beyond the control of the hosts, so no criticism - just one to be aware of.
This being said we had a super time in Porto and found the location to be excellent. If you are not planning to spend a long time in the room, this place would be good enough.
A few small changes and we would recommend this place without hesitation.