Communication: The day before check-in I received a message from my host that the water pipes had burst and the apartment was no longer available, but a second apartment of similar size and configuration was available. The replacement apartment was not listed on Airbnb, so we really did not know what we were getting into. Obviously this created considerably uncertainty for us. Compounding our anxiety, the host was not immediately reachable due to personal travel. Fortunately, Airbnb customer service quickly understood the issue and managed to track down our host while we were en route to Berlin. Upon arrival, they had confirmed that the replacement appeared to be of similar grade and configuration, and gave us the option to accept or reject the hosts alternative once we were on-site and had a chance to view the property directly. We ended up staying and it was fine, but the situation was stressful (traveling with my family, not knowing if we would have a place to stay...).
Value: Approximately 15% surcharge over what the direct cost might have been (according to the invoice I received during on-premise check-in). Ultimately I was OK with that premium because Airbnb stepped-in to ensure a positive outcome with the last minute changes described earlier. However, for a one-month stay (>$5K) the premium was sizable.
Summary: While, I could not provide a five-star review because of the issues mentioned above, I would like to thank our host for renting us this apartment. We enjoyed our stay in Berlin (#1 favorite city).