I will begin the review by stating that we did enjoy our stay. It is perfectly located to access the centre of Porto, and is easy to get to from the airport. There are many cafes, restaurants and shops within a minute from stepping outside, not to mention the market right across the street. It is a small apartment, but well planned out for 2 people to stay comfortably. It has lots of storage for clothing and suitcases and the bed is very comfortable. Ana was a delight to deal with, giving us recommendations and advice. She also came mid-week to clean, change the bedsheets and provide fresh towels. We appreciated this bonus.
Although we did have a comfortable, enjoyable stay, there are some items in the apartment overview/description on the website that are inaccurate. It does not have a washing machine as listed in the description and in the amenities. We do like to book rentals with a washing machine, so this was disappointing. We did find a laundrymat close by that worked out well, but had to take time out of our sightseeing to do so. Also, the description lists many toiletries provided, which was not the case during our stay - they did provide nice shower gel. As well, there was no bottle of Port on arrival. These things didn't really matter to us, but again, shouldn't be in the description if it isn't the case.
Other reviews mention the noise from the air conditioning units from surrounding buildings. This is indeed a fact, although it's a consistent noise, and almost became "white noise" after a while. Another reviewer mentioned they used earplugs, which would be a good idea at night if you need to keep the windows open.
Overall, the positives of this apartment outweigh the negatives and we did enjoy our stay.