Appartement was nice, very well located and pretty clean.
A few street noises during the night but overall it was ok. The bed is great but the sofa bed is not comfortable at all.
Communication was easy and responsive (we had a small leak and maintenance came under 24h) but be aware that Porto is one of these big cities where Airbnbs are often managed by external companies so the experience can be quite impersonal (check-in at another location, not many cooking equipment, never met the owner, etc.)
Still, the flat did the work perfectly for our short trip in Porto !