We did not meet Carlos/Cristina upon check-in, but everything went smoothly since there was a safe to get the key from. Pretty good location in Ribeira, walking distance to downtown (you will have to climb some steep streets to get there though), small studio but more than enough for a couple of nights. Since it was a pretty cold weekend in Porto, Carlos turned the heater on before our arrival, which was great! Only downside is the access to the apartment: it sits on a pretty old building (renewed), thus there are no lifts, you need to climb two or three steep flights of stairs to get to the apartment, so it is not recommended for people with reduced mobility. Anyway, if you want to stay in Ribeira or downtown Porto, you will probably have the same problem with 90% of the buildings.