The apartment and the host are great. Andre recommended great places to eat and give tips about sightseeing. I did not have any time to explore it myself because it was a business trip, but thanks to Andre I fell in love with Porto and I will definitely visit Porto again.
The flat is very clean, has everything you might need (there is no washing machine but there is a very good laundry just around the corner) and perfectly located. The bed is very comfortable and I slept really well.
The view from the balcony is inspiring and I had breakfasts there almost every morning.
The only thing I should mention is that it might be a bit noisy at Saturday night but it might be a problem only if you like to sleep with open windows.
If I am back in Porto I will stay there again.