The experience wasn’t really good.  When we arrived at the apartment, we've found hair on the bed and on the floor, the floor was dusty, the curtains, the towels and the window were really dirty, and even the mirror was broken. Plus, the toilet flush wasn't working when we arrive... after 8 hours of journey, you just want to relax… and to use the bathroom !
They sent someone to fix the flush in the evening (but they asked us first if we could fix it ourselves!).  They also sent a cleaning lady after we told them about the dirtiness of the apartment, but she just came to give us an other bed linen, but anything else got cleaned. Moreover, the linen that they sent contained some hair as well. It's not professional...
Last but not least, the flat is located just near a bus station. We heard the buses and their crazy drivers from 6AM until at least 9AM.. We couldn’t sleep very well.  We really don’t recommend this flat. We’re disappointed for our first time in Porto.